Support Herald rules for new Differential edits

Summary:
Ref T2222. Ref T4484. See D8404 for discussion.

When a revision is updated with the new Editor, apply Herald rules. Additionally, apply them in a modern way which generates transactions.

Test Plan:

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, chad

Maniphest Tasks: T2222, T4484

Differential Revision: https://secure.phabricator.com/D8405