R1:c2d66f29cd80

Make `phd` more aware of multiple daemons under a single overseer

Summary: Ref T7352. This makes `phd stop` and `phd status` produce more reasonable output with the new PID file format.

Test Plan: Ran `phd stop`, `phd status`, etc.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7352

Differential Revision: https://secure.phabricator.com/D11856