[migration] Move pyramid-related migration after "entities" table modifications
Otherwise, we getting into `add_entity_type('CWSession')` we try to insert a
CWEType without any 'asource' column (per 3.24's schema) whereas the backend
still wants it.
Closes #17054035.
[entities] Introduce an IDublinCore adapter
Move all dc_ methods from AnyEntity to the new IDublinCore adapter and proxy
them through a __getattr__ method on AnyEntity.
Current test suite should be enough.
Closes #3119992.