GitLab

Basically:

mkdir cubicweb
hg mv *.py -X setup.py cubicweb
hg mv dataimport devtools entities etwist ext hooks i18n misc schemas server skeleton sobjects test web wsgi cubicweb

Other changes:

* adjust path to cubicweb-ctl in devtools tests
* update setup.py to avoid importing __pkginfo__ (exec it instead),
  replace os.path.walk by os.walk and prepend `modname` here and there
* update tox.ini to account for new test locations
* update doc/conf.py so that it still finds __pkginfo__.py and CWDIR in
  doc/Makefile

Stolen from the massive import store, with the irrelevant bits removed.
Remove redundant tests from test_pgstore.py.

Some tweaks have been made to work with 3.21 foreign key constraints.
Also test are not executed in our own pg cluster instead of polluting the system
one.

Closes #5414760