Make "ADD_CC" and "REMOVE_CC" available as "standard" Herald effects
Summary:
Ref T8455. Begins consolidating the code for applying these effects:
- Makes Add/Remove subscribers a standard effect, and uses it in Pholio.
- This includes the "don't re-subscribe users who have explicitly unsubscribed" logic from Differential in the standard effect. I think this rule is always desirable.
- This adds new filtering of invalid PHID types to resolve the arc diff issue in T8455 once Differential uses this standard effect.
- Added "Remove Subscribers" to MockAdapter in order to test that it works.
- Relabeled "CC" in Pholio to "Subscribers" for consistency.
Test Plan:
- Created several rules which add subscribers to (and remove subscribers from) mocks.
- Updated mocks, changing properties and adding and removing subscribers.
- Observed transactions applying and aggregating properly.
- Observed add/remove rules each working correctly.
- Observed the "don't re-add unsubscribed users" condition acting on subscribers who had previously been added but explicitly removed/unsubscribed.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T8455
Differential Revision: https://secure.phabricator.com/D13179