R1:5348f34c9eec

Make all revision status readers explicitly read modern or legacy status

Summary: Ref T2543. All writers now write modern statuses. Make all readers explicit about whether they are reading modern or legacy statuses, so I can swap the storage format.

Test Plan:
- Grepped for `getStatus()`, scanned the list. Other applications have methods with this name so it's possible I missed something.
- Browed around, changed revision statuses.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T2543…