Stronger scoping for Conpherence chat forms

Summary: Fixes T12391. Adds better scoping to these rules to contain changes to just Conpherence.

Test Plan: Test Conpherence, Task comment, persistent chat on mobile / desktop.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12391

Differential Revision: https://secure.phabricator.com/D17496