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