Add a UI for reviewing database schemata
Ref T1191. Plan here is:
- Build a tool showing the current schemata status (this diff).
- Have it compare the current status to the desired status (partly here, mostly in future diffs).
- Then add a migration tool, and eventually a setup issue to tell people to run it.
Reviewed current schemata.
Reviewed By: btrahan
Maniphest Tasks: T1191
Differential Revision: https://secure.phabricator.com/D10494