Summary:
Ref T10939. Fixes T7834.
- Make packages into mailable objects, like projects and users.
- Packages resolve recipients by resolving project and user owners into recipients.
Test Plan:
- Added a comment to a revision with a package subscriber.
- Used `bin/mail show-outbound` to see that owners got mail.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T7834, T10939
Differential Revision: https://secure.phabricator.com/D15912
547abfe873