[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

[massive store] Store entities in temporary table as well * on some entity type is encountered by a slave, create a dedicated table for insertion of entities of this type by this slave, similarly to what is done for relation - this should lower changes of conflicts in master/slaves mode ; * delay drop of constraints and indexes to `finish` method, where copy from temporary tables to regular table is done ; * insertion of metadata is done by scanning temporary tables, which may be way shorter than theier associated regular table ; * drop drop_metadata_constraints with its constraint_dropped friend attribute, there are no more necessary since this is done once in the `finish`. Related to #15538303

[massive store] Drop useless check for empty buffer If something went wrong, an error will be raised.

[massive store] Docstring / comment cleanups