provenance: add (revision) dates to the relation tables
To be able to effectively answer the "first occurrence" query in the provenance db, we need to add an indexed column with the date of the revision in the
content_in_revision (that is, turn it into
(content_id, revision_date, revision_id, location_id)).
We should consider whether we need to do that for
directory_in_revision as well.
Migrated from T4707 (view on Phabricator)