* Fixes https://erp5js.nexedi.net/#/bug_module/20160609-11B02E6 and https://erp5js.nexedi.net/#/bug_module/20210517-F12266
* Support ERP5JS
* Improve test coverage
* Small CSS changes
* Fix bug editing business process when erp5_graph_editor was installed 

See merge request !1461

Until now, portal_sessions was only reliably usable when using a family with only one zope node, because the session data was using RAM cache.
When used by authenticated users it was more or less usable, because of haproxy
sticky cookie that we set for authenticated users, but for non authenticated users
this was basically unusable.
This was especially a problem for CaptchaField, for which users are generally not
authenticated.

This changes portal_sessions to use a distributed cache, which brings several
differences:
 - sessions are now shared between all zopes of a cluster.
 - storing ERP5 temp documents is still possible, but modifying a temp document in
   session does not automatically save the changes in session, for next session read
   to be using the modified document it's required to save the document explicitly.
 - session respects transaction semantics, changes are only persisted in session when transaction commits successfully.
 - `portal_caches.clearAllCaches` API no longer clear all sessions.

See merge request nexedi/erp5!1451

See merge request !1466

See merge request !1464

There was a wrong assertion in an interaction workflow, preventing saving from
other tabs than the graph editor

- set validator, this is now required to be able to edit
- use an iframe for ERP5JS compatibility
- clean up this form, it had some unused disabled fields, remove them
completly instead

and also enable coding style on this bt

- set validator, this is now required to be able to edit
- use an iframe for ERP5JS compatibility

- set validator, this is now required to be able to edit
- use an iframe for ERP5JS compatibility

Graph layout is part of the workflow, a bit like the description.

These are rendered with a loop from the state to the state, it's ugly and not
much informative, remove them for now. We could use different edge styles for
"worklow method only" and "workflow method and user action" transitions and
render this as only one transition. We could also change the data model of
workflow itself, now that this is no longer using DCWorkflow.

This is required with ERP5JS, where every save call render with new data.

When no schema for the edge, don't try to show edge edition dialog. Until now
this was crashing

 - make the gadget full page, this is better when using in an iframe
 - "highlight" the currently hover edge, which makes the graph more readable
 when there are overlapping edges.
 - user helvetica font every where

This introduces a new gadget_graph_editor.html gadget, for use in iframe and
keep the existing dream_graph_editor/jsplumb/index.html for use in "public"
scope, ie. without iframe.

as explained in comment, this API is asynchronous but the promise to await is
not exposed

At the beginning of tests, there is Tests completed in {a few milliseconds}, so
this was reporting success before the test even run.

 - We don't care about a stable random layout, we want to include the
manual layout in business templates
 - Re-add edge edition dialog that was removed
 - Drop a wrong CSS that was removed long time ago but re-added by mistake
 - Don't do CSS in the javascript, the graph model allows to have CSS in
the model

book_signature_list, book_version_list, book_distribution_list are not done and always empty