R1:8965c7ec9b89

Email Preferences - round out options for Projects and Phriction

Summary: Fixes T8524, T8550. These were both missing "subscribers" and Phriction was also the only application with no "other".

Test Plan:
- Project
- set user A to notify only for project subscriber changes
- made a project with user A
- subscribed user B to project
- verified notification sent to user A
- used ./bin/mail to make sure no mail was sent to user A because "This mail has tags which control which users receive…