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.
Instead of 41 queries now for the simple manifest, we are down to 14.
The biggest changes:
- Only synthesize the V1 image rows if we haven't already found them in the database
- Thread the repository object through to the other model method calls, and use it instead of loading again and again
Will let the users know they can recover the tag via time machine
Note: This was tested with the Docker protocol, but the new error code is *technically* out of spec; we should make sure its okay.
