Modularize Conpherence notification preferences

Summary:
Ref T4103. This is a weird standalone setting that I didn't clean up earlier.

Also fix an issue with the PronounSetting and the Editor not interacting properly.

Test Plan: Edited using new EditEngine UI.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T4103

Differential Revision: https://secure.phabricator.com/D16014