[entity] Entity.related(): add a targettypes argument (closes #2957313) This allows to restrict the entity types returned by the method (passed to cw_related_rql). When such an argument is given, no caching happens.

sync_schema_props_perms(('State', 'state_of', 'Workflow'), commit=False)
sync_schema_props_perms(('State', 'name', 'String'))