Summary: Ref T5867, adds a customPHID field, nullable, and lets you query by it... i think? Not fully able to grok all the EditEngine stuff, but I think this is the right place for the query.
Test Plan: Not wired to anything, but pulling up project menu, editing, all still works.
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin
Maniphest Tasks: T5867
Differential Revision: https://secure.phabricator.com/D17149
