[test] Remove some usages of lgc.testlib

[test] Avoid pytest discovery warnings Having TestServerConfiguration and alike in the test module namespace causes pytest discovery errors, because it thinks it's a test class.

flake8 and all * update some copyright * drop most __docformat__ declaration * fix some flake8 warnings / errors

[schema2sql] Drop deprecated comment

[cnx] Use entity_type instead of entity_metas()['type'] The latter is deprecated in favor of the former which has been introduced on cnx to replace it.

[entity] Reimplement and deprecate entity.cw_metainformation It shouldn't rely anymore on cnx.entity_metas which is itself deprecated, and the cw_metainformation API is similarly not needed anymore, access directly to cwuri / cw_source if needed. Related to #15538288

[repository] Drop type_and_source_from_eid and rename related cache We don't want to handle anymore the entities.asource column so we shouldn't use those anymore. Also rename repository's _type_source_cache into _type_extid_cache as this is what it's containing now. Do similar renaming to the system source API. Related to #15538288

[entity] Stop returning source information in cw_metainformation() We should not need that. It has been introduced to handle things we should not do and probably don't do anymore (e.g. attempting to grasp recursive import of several sites). Related to #15538288.

[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