Add support for kafka journalization of the ProvenanceStorageInterface

the new ProvenanceStorageJournal is a proxy ProvenanceStorageInterface that will push added objects in a swh-journal (typ. a kafka).

Journal messages are simple dicts with 2 keys: id (the sharding key) and value (a serialiazable version of the argument of the xxx_add() method).

Depends on !152 (closed) Related to #4616 (closed)

---

Migrated from D8657 (view on Phabricator)

swh/provenance/storage/__init__.py

@@ -48,5 +48,14 @@ def get_provenance_storage(cls: str, **kwargs) -> ProvenanceStorageInterface:
         if TYPE_CHECKING:
             assert isinstance(rmq_storage, ProvenanceStorageInterface)
         return rmq_storage
+    elif cls == "journal":
+        from swh.journal.writer import get_journal_writer
+        from swh.provenance.storage.journal import ProvenanceStorageJournal
+
+        storage = get_provenance_storage(**kwargs["storage"])
+        journal = get_journal_writer(**kwargs["journal_writer"])
+
+        ret = ProvenanceStorageJournal(storage=storage, journal=journal)
+        return ret
 
     raise ValueError