Retrieve content with other checksums than sha1

Improve the storage implementation to permit the user of other checksums as filter (only sha1 atm)

---

Migrated from T209 (view on Phabricator)

mentioned in issue swh-web#198 (closed)

added Storage manager priority:High labels

changed title from Open swh.storage.storage.content_get to deal with other checksums than sha1 to Retrieve content with other checksums than sha1

changed the description

assigned to @ardumont

mentioned in commit d303347d

mentioned in commit swh-objstorage@3755a194

mentioned in commit c503fac8

mentioned in commit swh-objstorage@272df815

mentioned in commit swh-web@5c96db2c

mentioned in commit swh-web@000db839

closed