Deduplicate RawExtrinsicMetadata by hash instead of a subset of their fields

---

Migrated from T3022 (view on Phabricator)

assigned to @vlorentz

marked this issue as related to #3019 (closed)

marked this issue as related to #3020 (closed)

marked this issue as related to swh/meta#2703 (closed)

added Extrinsic metadata Storage manager priority:High labels

After the release of swh.model v2, this is now done.

closed