R1:4dd87f1ad3ca

Drive Differential landing page with DifferentialRevisionQuery, simplify UI

Summary:
- Use DifferentialRevisionQuery, not DifferentialRevisionListData, to select
revisions.
- Make UI simpler (I hope?) and more flexible, similar to Maniphest. It now
shows "Active", "Revisions", "Reviews" and "Subscribed" instead of a hodge-podge
of miscellaneous stuff. All now really has all revisions, not just open
revisions.
- Allow views to be filtered and sorted more flexibly.
- Allow anonymous users to use the…