Delete various dead/nonuseful PHID code

Summary:
Ref T2715.

• Remove the "PHID" application. phid.query provides a reasonable way for developers to get this data without requiring a top-level application.
• Remove some dead/uncalled code.

Test Plan: No more PHID application. Grepped for callsites.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2715

Differential Revision: https://secure.phabricator.com/D6511