something like this is required for shared parts to be effective

Move `numpy=1.16.4` from all over the place into component/numpy.
Don't move if a different numpy version is used, or it looks like a
software cares to use exactly particular version.
Downgrade pygolang/test.cfg from numpy=1.16.6 to numpy=1.16.4 and use
common numpy component version - using numpy=1.16.6 is not required for
pygolang testing and so this downgrade is acceptable. It will be better
to upgrade NumPy to latest in component/numpy/ as a future separate step.

See previous patch where it was decided and explained that version for
component <X> lives in component/X/.

Move versions for eggs that component/{ZEO,pygolang,zodbtools,pytest}
depend on out of component/ and into stack/slapos.cfg

Leave version of component <X> inside component/<X>.

I was asked to do so:

!839 (comment 119170)

I tried to use this gdb in a software release installed by slapos-sr-testing (which perform some extra checks that we only do in slapos-sr-testing at the moment) and it complains that:

```
======================================================================
ERROR: setUpModule (test)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/srv/slapgrid/slappart9/srv/slapos/soft/24930952d96110d7e0142b49eba918a8/parts/slapos.core-repository/slapos/testing/testcase.py", line 168, in setUpModule
    installSoftwareUrlList(cls, [software_url], debug=debug)
  File "/srv/slapgrid/slappart9/srv/slapos/soft/24930952d96110d7e0142b49eba918a8/parts/slapos.core-repository/slapos/testing/testcase.py", line 378, in installSoftwareUrlList
    checkSoftware(cls.slap, software_url)
  File "/srv/slapgrid/slappart9/srv/slapos/soft/24930952d96110d7e0142b49eba918a8/parts/slapos.core-repository/slapos/testing/testcase.py", line 336, in checkSoftware
    raise RuntimeError('\n'.join(error_list))
RuntimeError: /srv/slapgrid/slappart9/srv/slapos/inst/slappart7/tmp/shared/gdb/d14016b094c3637c4ebf6a3df4a8c64d/bin/gdb uses system library /usr/lib/x86_64-linux-gnu/libexpat.so.1.6.8 for libexpat.so.1

----------------------------------------------------------------------
Ran 0 tests in 462.686s
```

I saw this on a debian KVM on which I don't think I installed any system package except `slapos-node`, but `libexpat1-dev` is installed for some reason, so configure detected it and the built binary is linked against it. I checked some test nodes and `/usr/include/expat.h` seems present on some testnodes, so probably some test nodes will also have this problem. For that, I suggest to build a gdb using slapos `libexpat`, so that we build something more reproductible and not depending on the host system (that's important if we want to use binary cache, but can also be a problem if system packages get remove/upgraded). As you might be thinking now, that's a kind of infinite problem, because we can not add anything that configure might detect, but that's how we usually do for this for now.

While looking at this, I also realised that we were using a .tar.xz URL here, for which rely our recipe will use `xz` command. Because some machines might not have that command, we usually put `xz-utils` in PATH.

How about including something like this ?

Just like with pygolang and zodbtools add way to run wendelin.core tests
via nxdtest with test instance organized with help of stack/nxdtest.cfg

Test agains ZODB4 and ZODB5 for the reasons explained in previous patch.

Wendelin.core already had [wendelin.core-dev], so we only have to add
test*.cfg in this patch.

Following approach used for pygolang in the previous patch lets add
testing support for zodbtools:

- Add zodbtools/buildout-dev.cfg that overrides [zodbtools] to use the
  software from git checkout.

- Add zodbtools/test<X>.cfg that is software-release to create a test
  instance to be run under testnode. To help itself on this task this
  software release uses just-added stack/nxdtest.cfg and
  [python-interpreter] from pygolang, so the code in zodbtools is
  minimal.

Zodbtools can be tested against both ZODB4 and ZODB5 because we still
use ZODB4 as our primary ZODB version, but it is no longer supported by
upstream which considers only ZODB5 as current.

- Add pygolang/buildout-dev.cfg that overrides [pygolang] to use the
  software from git checkout.

- Add pygolang/test.cfg that is software-release to create a test
  instance to be run under testnode. This software release uses
  just-added stack/nxdtest.cfg to help itself on this task, so the code
  in pygolang is minimal.

A new section [python-interpreter] is added, because python interpreters
that zc.recipe.egg generates don't process `-m args` correctly and
handle subprocess well. I had to workaround that with code from
gpython.pymain to be able to run `python -m pytest --<pytestarg>` and to
spawn children processes with preserving sys.path. Comments around and
inside [python-interpreter] has more details on this topic.

Pytest is used to test wendelin.core, zodbtools and pygolang
It is also used in component/unstable/pyodide, but currently via pip.

Currently Nexedi takes mostly a copy-paste approach when it comes to
organizing bin/runTestSuite and an instance to run this inside testnode:

    kirr@deco:~/src/wendelin/slapos/slapos-master$ git ls-files |grep runTestSuite
    software/build-rina/runTestSuite.in
    software/buildout-testing/runTestSuite.in
    software/cython-test/runTestSuite.in
    software/erp5testnode/testsuite/deploy-test/runTestSuite.py
    software/jstestnode/runTestSuite.in
    software/neoppod/runTestSuite.in
    software/neoppod/stress-testing/runTestSuite.in
    software/unstable/pyodide/runTestSuite.in

and adding new tests to be run this way will only increase the entropy.

Let's stop this, at least for new tests, and use a uniform approach without copying:

1) I've created nxdtest tool[1] which allows a project to specify in
   declarative way how to test itself: given such declaration nxdtest
   takes on itself the responsibility to communicate with testnode
   master, to drive test commands spawning etc, and leaves to the
   project only semantic part that is specific to the particular
   project.

   Nxdtest is based on my go/neo/t/nxd/runTestSuite[2,3] and on the code
   I've seen elsewhere scattered in other runTestSuite.in files.

2) Let's add stack/nxdtest.cfg to SlapOS that provides easy way for a
   software or component to organize testing of itself.

This patch adds stack/nxdtest and migrates software/neotest to use it
(because stack/nxdtest is based on it and this way it helps to track the
changes).

In the following patches we will add testing support for pygolang,
zodbtools and wendelin.core .

[1] https://lab.nexedi.com/kirr/nxdtest/blob/master/nxdtest
[2] kirr/neo@51b18490
[3] kirr/neo@f67c147d

${go:exe} is standalone executable that runs go in activated gowork environment.
It is handy to use in recipes where one cannot source ${gowork:env} -
in particular parts with recipe=zc.recipe.egg

Wendelin.core 2 will use `GO=${go:exe}` in its build environment.

GDB is used in wendelin.core tests:
https://lab.nexedi.com/nexedi/wendelin.core/blob/v0.13-49-g35cb144/t/tfault-run#L28

Starting from 0.14 (aka 2) wendelin.core requires pygolang to be present
both at runtime and at build time.

Update lab.nexedi.com/kirr/neo.git and lab.nexedi.com/kirr/go123 to latest.
Update all other go packages.

The update puls in the following new dependencies:

    github.com/shamaton/msgpack
    github.com/tinylib/msgp
      github.com/philhofer/fwd
      github.com/ttacon/chalk
      golang.org/x/mod
      golang.org/x/xerrors

    github.com/davecgh/go-spew
    github.com/pmezard/go-difflib
    gopkg.in/yaml.v3

Going from 0.0.0.dev4 to -> 0.0.0.dev8 zodbtools:

- Stabilized `zodb dump` format and layed ground for `zodb restore`;
- Taught `zodb analyze` to work with any ZODB storage (instead of being
  FileStorage-only tool) and to analyze a particular range of history
  (instead of crunching data for days on a large database);
- Added `zodb commit` tool that is handy in testing;
- Added ability to specify tid ranges in human-readable format, as in
  e.g. `zodb analyze data.fs 2018-01-01T10:30:00Z..yesterday`.
- Progressed on Python3 support.

See https://pypi.org/project/zodbtools/#zodbtools-change-history
for details.

Close to non-functional change, but removes PendingDeprecationWarning
about cgi.parse_qsl

0.0.0.dev4 to 0.0.7.post1 goes a long way. See
https://pypi.org/project/pygolang/#pygolang-change-history for details.

Recent pygolang is needed for wendelin.core 2.
Zodbtools also uses it starting from v0.0.0.dev5.

We already patch ZEO4 with TCP_NODELAY patch (see 5cf4cf1f "ERP5:
enable TCP_NODELAY for ZEO") and we will need to backport more patches
to ZEO4 branch for wendelin.core 2 to work correctly.

It's not only software/neoppod which uses ZEO, and it is not convenient for
all other software-releases to inherit from neoppod to use correct
version and build of ZEO egg. For this reason factor out details of ZEO
egg building into component/ZEO and let users use ${ZEO:egg} where ZEO
is needed. This way ZEO will be correctly installed for all users.

This patch should be a non-functional change. We switch to
nexedi/ZEO@5114f909 revision which corresponds to ZEO 4.3.1 +
TCP_NODELAY.patch

Adding other patches to ZEO4 needed by wendelin.core 2 will be done as a
separate step.

See merge request !836

stop-on-error during instantiation can lead to endless instantiation in some
cases, which disallows to create services required for given part to pass, and
in the same time in many cases the called scripts are smart enough to continue
and restart on error.

Thanks to this, it's much easier to find relevant configuration, and also logs
are becoming much more informative.

Avoid creating needless entries and minimise needless newlines, and reflect
this in test data, as in such case no backend_log is created, as nothing is
configured on backend Haproxy level.

SSL cache is unusable in context of caddy, same for the so called HTTPD home.
Those are old Apache leftovers.