Accommodate project reviewers in Differential search
Ref T1279. Two changes to the search/query for Differential:
- "Reviewers" now accepts users and projects.
- "Responsible Users" now includes revisions where a project you are a member of is a reviewer.
- Searched for project reviewers.
- Verified that the dashboard now shows reviews which I'm only part of via project membership.
Reviewed By: btrahan
Maniphest Tasks: T1279
Differential Revision: https://secure.phabricator.com/D7231