Move field editing to ReviewRequestEditorView.

This moves all our field editing code to ReviewRequestEditorView. This
includes the completion formatters, auto-complete, and then everything
we no longer need in reviews.js such as publishDraft and the draft
banners.

Instead of the old model where there were "edit complete handlers" and
we just operated on anything with ".editable", we now have a basic field
registration system. All the fields we have today are registered, and
part of that registration are things like "Only use the edit icon to
enable editing" or "here's the formatter." This keeps things sane and
readable, and down the road will let us dynamically add new fields.

Unit tests were added as well for the new fields and events.

There's some work planned for later to simplify field IDs on the
elements, so there's consistency between field names in the model and
elements, which will let us remove some of the required metadata and
guessing in field registration.