Move Projects to SearchFields

Summary:
Ref T8441. Ref T7715. This is mostly about getting SearchFields + CustomFields working.

(This includes a couple of SearchFields which aren't used quite yet.)

Test Plan:

• Used all search controls.
• Defined custom fields and searched for them.
• Created an old saved search which searches on custom fields on master, switched to this patch, search worked exaclty as written.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7715, T8441

Differential Revision: https://secure.phabricator.com/D13189