[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
../libpython/cubicweb_file