Modernize all Herald DifferentialDiff fields
Summary: Ref T8726. This deals with all the Differential diff fields, same deal as previous changes.
- Wrote a rule with every field.
- Migrated it.
- Saw the same rule working.
- Rigged the hell out of transcripts (diffs normally do not generate transcripts, because the only action is "block" and they don't exist yet when Herald runs).
- Verified that all fields looked sensible in the transcript.
Reviewed By: btrahan
Maniphest Tasks: T8726
Differential Revision: https://secure.phabricator.com/D13590