R1:2492fef029b1

Move Pholio to SearchFields

Summary:
Ref T8441. Ref T7715.

- Update PholioSearchEngine.
- Automatically add project fields.
- Update Paste to support project search.
- Simplify common Query class construction.

Test Plan:
- Searched for pastes.
- Searched for mocks.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7715, T8441

Differential Revision: https://secure.phabricator.com/D13174