[debian] Have a single python-cubicweb binary for the library But keep distinct meta-packages for dependencies of the HTTP server (Twisted/Pyramid) and database backend. Related to #16133259.

[debian] Update debian packaging (closes #16133259) - use dh_python, pybuild and debhelper>=9, - refactor and simplify the debian/rules, - rename binary packages (but cubicweb-ctl) to python-xxx - remove daemon handling stuff (initscripts...) from cubicweb-ctl (one should now use a standard WSGI delivery method),

[pkg] Version 3.24.1

[tox] Use `python -m check_manifest` instead of check-manifest program To make sure we use Python from tox's virtualenv.

add debian buildpackage-generated files to hgignore

[test] Fix language negotiation test At least when executed alone (there seems to be a test isolation problem which I could not figure out).

[pyramid] No more need for an internal connection when user is cached

[web] req.lang should be None or a non-empty string

[web] Simplify a bit language handling Drop `set_default_language` and `set_user_language` by considering that: * before being bound to the user, request will have the site's default language * cnx has the user's preferred language, hence get it back to the request when it's bound to a connection The first point requires some change to cubicweb's vreg faking so it doesn't break. That should be enough.

Fix AttributeError for "lang" on repo/client connections This is a regression introduced by b48020a80dc3, which removed call to set_language from the `req._set_user` method. This is fine, but we still want a language on connections, so we've to handle it if necesary in Connection.__enter__ (i.e. once connection is properly open). When using pyramid front-end, which has a users cache, we've to cache its language as well because we must not access its preferred_language method since it's not bound to a proper connection.