bpo-32468: Better frame repr()

Starting with AIX6.1 there is support in libc.a for uuid (RFC4122)
This patch provides the changes needed for this integration with the OS.

On AIX the base function is uuid_create() rather than uuid_generate_time()
The AIX uuid_t typedef is more aligned to the UUID field based definition
while the Linux typedef that is more aligned with UUID bytes
(or perhaps UUID bytes_le) definitions.

Port importlib_resources to importlib.resources

* Add abstract get_loop() method to Server, AbstractServer classes.
* Add test cases for get_loop() method in Server, AbstractServer classes
* Add documentation for get_loop() method

In pydoc.py, the reference to Python' documentation was in http.
The link has been updated to use https.

* Fix typos
* Change warning text
* Add test

_PyUnicode_FromId() may return NULL.

Reported by coverity scan: CID 1426868, 1426867.

This is more complicated than it should be because we need to preserve the
useful mtime-based regeneration feature that lib2to3.pgen2.driver.load_grammar
has. We only look for the pickled grammar file with pkgutil.get_data and only if
the source file does not exist.

Skip the test which fails on FreeBSD with POSIX locale.

Skip the test to fix FreeBSD buildbots, until a fix can be found, so
the buildbots can catch other regressions.

Skip the test failing randomly because of known race condition.

Skip the test to fix macOS buildbots until a decision is made on the
proper fix for the race condition.

Add a new _Py_FindEnvConfigValue() function: code shared between
Windows and Unix implementations of _PyPathConfig_Calculate() to read
the pyenv.cfg file.

_Py_FindEnvConfigValue() now uses _Py_DecodeUTF8_surrogateescape()
instead of using a Python Unicode string, the Python API must not be
used early during Python initialization. Same change in Unix
search_for_exec_prefix(): use _Py_DecodeUTF8_surrogateescape().

Cleanup also encode_current_locale(): PyMem_RawFree/PyMem_Free can be
called with NULL.

Fix also "NUL byte" => "NULL byte" typo.