Replace old commit edit controller with new EditEngine controller
Summary: Ref T10978. The new controller now does everything the old one did, so swap 'em and nuke the old one.
Test Plan: Edited a commit, hit the new controller, things worked real good.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T10978
Differential Revision: https://secure.phabricator.com/D17177