Decrease fragility of `conpherence-pontificate` behavior

Summary:
Currently, this behavior binds a ton of IDs. This makes the behavior fragile: if it is invoked on a page without all the right elements, some `JX.$()` tends to explode.

Instead, don't assume anything is present on the page. This allows the behavior to be invoked on other pages (like the "New Conpherence" page) or pages without some elements (like some future thread-only mobile view) without creating JS errors.

Test Plan:
Added comments, added comments with files. Viewed "New conphenrece" page.

NOTE: Control+Enter is currently broken, but this diff didn't change that behavior.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D5468