R1:8ad5d28686a4

Migrate old reviewer edges to new storage

Summary:
Ref T10967. We still have double writes, so all reviewers are being written to both old and new storage. This migrates all the data in the old storage to the new storage, so both storage tables should have a complete set of data and be getting identical updates as we move forward.

After this, I can move readers over one at a time and eventually get rid of the old writes and old storage.

This loads all of the edge data into memory in a big chunk. I…