Add support for swh.model.model objects in the DirectWriter.
They are used by the in-memory storage, and may be used by others later.
Migrated from D1903 (view on Phabricator)
Staging instance, all changes can be removed at any time
They are used by the in-memory storage, and may be used by others later.
Migrated from D1903 (view on Phabricator)