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").

• 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.