[req,web/request] Move language prefix handling into web request This changes part of d8830e2bd2e0 by unsetting "lang" attribute of RequestSessionBase in particular (because it appears to break many downstream applications). The new implementation relies on a new "build_url_path" method on RequestSessionBase that is overridden in _CubicWebRequestBase to handle the language prefix in URL. As a consequence build_url in RequestSessionBase is not aware of this prefix anymore (contrary previous implementation from d8830e2bd2e0). Move respected tests from unittest_req.py into unittest_request.py. Commenting out part of test_handle_request_no_lang_negotiation_fixed_language in unittest_application.py because it now fails because of some obscure bug that cannot be resolved at the moment. Related to #15743487.

[test] Use stdlib unittest instead of lgc.testlib in unittest_request.py

[test] Distinguish "request" tests from accept parser ones in unittest_request.py

[pkg] Add setuptools to RPM build requirements

[pkg] Version 3.24.0

[req,web] Make it possible to handle page language from URL prefix Adding a short language prefix to URL (like "/en" or "/fr") changes the language the pages are displayed in. This prefix is kept during navigation. This way it is not necessary to do language negotiation, nor to use user preferences to determine which language to apply. This behavior is controlled through a new configuration option "language-mode", which replaces "language-negociation" option and which values may be "http-negotiation", "url-prefix" or "" (to disable language setting and force using "ui.language" property). Migration from previous option is not handled because I could not manage to have it working (users will get prompted with the configuration file diff anyways). Add some tests checking various scenarios. Closes #15743487

[config] fix the load_site_cubicweb() method for to 'new-style' cubes (closes #16059402) We first try to load the site_cubicweb module from the cubicweb_<cube> package, and if it fails, revert back to old cube path.

[massive store] remove on_commit / on_rollback parameters No actual use of this was found in client code. If one wants to control this behaviour, he can always override the commit method and add a try / except around flush_entities in its own store

[massive store] master_init should commit by default Default client usage is to create a master store to control slave ones. They need to access cwmassive_initialized from another transaction

[massive store] isolate SQL statements that one may want to customize i.e. provide public methods for meta data insertions