Add new Manifest, ManifestLabel, ManifestLegacyImage and ManifestBlob tables and start writing and GCing to/from them

This change also starts passing in the manifest interface, rather than the raw data, to the model for writing.

Note that this change does *not* backfill the existing rows in to the new tables; that will occur in a followup PR. The new columns in `tagmanifest` and `tagmanifestlabel` will be used to track the backfill, as it will occur in a worker.

data/model/test/test_basequery.py

@@ -89,6 +89,9 @@ def test_filter_repositories(username, include_public, filter_to_namespace, repo
            .switch(Repository)
            .join(RepositoryPermission, JOIN.LEFT_OUTER))
 
+  # Prime the cache.
+  Repository.kind.get_id('image')
+
   with assert_query_count(1):
     found = list(filter_to_repos_for_user(query, user.id,
                                           namespace=namespace,