[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.