Add draft and close banners to review UI pages.

The review UI pages for file attachments didn't have draft or close banners,
which made it kind of confusing, especially in the case when the review request
wasn't yet published. This change adds them, and fixes up some of the issues
that resulted from it.

Testing done:
Tested draft, public, and closed review requests with both the text and image
review UIs. Saw all the expected banners and no javascript errors.

Reviewed at https://reviews.reviewboard.org/r/6033/