Move Conpherence Threads to new phid stuff

Summary: Ref T2715.

Test Plan: loaded conpherence, loaded a different thread, made a conpherence. also phid.query

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2715

Differential Revision: https://secure.phabricator.com/D6577