[json] Stop serializing cw_source into default json representation of an entity Related to #15538288

Drop deprecated LDAP related script both are relying on the 'entities.source' column which has been dropped in 3.19. They have been written with the old ldapsource in mind, which has been dropped at that time.

[entity] Stop linking to external site for external entities This behaviour was ok when we had "true" multi-sources but its rather painful with datafeed sources. Also, it makes absolute_url() costlier than what it should. Besides, it relies on cw_metainformation()['source'] that is pending for removal. Instead, add a link to the original object in the metadata view (the one that displays eid and source at the bottom right corner of the primary view). Related to #15538288.

[datafeed] Drop entity deletion handling in the default source / parser This should be handled by specific parser to avoid using "entities.asource". Reimplement it in the ldap parser. Related to #15538288

[sources] Drop 'moved_entities' table handling This was clumsy and could be handled using exturi / cwsource, as the ldap source now does.

[repository] Drop deprecated extid2eid API and friends This will break cwxmlparser based sources. They should be rewritten using a specific parser, based on xml representation or on rqlio. This is harsh but allows a so big cleanup of the code base. Furthermore, it's necessary for asource/extid handling in the entities table which is costly for most app that don't care at all about that... In this cset, delete: * all extid2eid methods * repo._extid_cache handling * [before/after]_entity_insertion source callback * the cwxmlparser and update related tests, notably unittest_datafeed where 'repull' testing has been removed, since it's now handled by the dataimport API and should not be retested there. Related to #15538288 Closes #15538383

[ldap] Stop using entities table in ldap source authentication and parser We may used cwuri for the same purpose, and do one more step towards deletion of entities.extid column. Related to #15538288

[test] Use stdlib unittest in unittest_webconfig.py

[tox] Require ldap3 < 2 for server tests Apparently we are using some constants that got dropped/moved in ldap3 >= 2.0.0 (which came out last week). So stay with version 1.4 until this gets sorted out.

[setup] fix CWDevelop to keep compat with python 2.7 in Python, 2.7, setuptools.command.develop.develop is an old style class, thus it cannot be called with super.