[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
from yams.buildobjs import ComputedRelation, EntityType, RelationDefinition
from cubicweb.schema import RRQLExpression
class Subject(EntityType):
pass
class Object(EntityType):
pass
class relation(RelationDefinition):
subject = 'Subject'
object = 'Object'
class computed(ComputedRelation):
rule = 'S relation O'
__permissions__ = {'read': (RRQLExpression('S is ET'),)}