R1:b8b4279a8ad2

Use SearchFields in Maniphest

Summary:
Ref T8441. Ref T7715. Move Maniphest to SearchFields.

The only new tech here is hiding fields, which we use to hide some fields on the dashboard query UI.

Test Plan:
- Queried by each field, including custom fields.
- Used some standrad queries.
- Used dashboards, used standard + custom queries.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7715, T8441

Differential Revision: https://secure.phabricator.com/D13225