[provenance] Fallback to swh-storage if a revision or its parent is not found in swh-graph
Only one archive storage is requested to resolve revision or revision parents.
If the default backend is the graph, it's not sure it's up to date so the revision resolution could not match the reality of the archive.
To solve that, if a revision is not found in the graph, the search should also be done in swh-storage
Migrated from T4315 (view on Phabricator)