Move all revision status transactions to modern values and mechanics

Summary:
Ref T2543. This updates and migrates the status change transactions:

• All storage now records the modern modular transaction ("differential.revision.status"), not the obsolete non-modular transaction ("differential:status").
• All storage now records the modern constants ("accepted"), not the obsolete numeric values ("2").

Test Plan:

• Selected all the relevant rows before/after migration, data looked sane.
• Browsed around, reviewed timelines, no changes after migration.
• Changed revision states, saw appropriate new transactions in the database and timeline rendering.
• Grepped for differential:status.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T2543

Differential Revision: https://secure.phabricator.com/D18419