Preserve the rich_text setting from the draft when publishing.

The rich_text setting in ReviewRequestDraft was never being set on the
ReviewRequest or on the ChangeDescription. With the new default of
False, any rich text made on a draft would end up being escaped on a
review request, and any escaped content would be double-escaped.

Ran rbt post -g to my local server. Verified text started out escaped.

Filled out Testing Done. Description was still escaped.

Published. Saw that rich_text was true, and the escaping was preserved.

Checked how it was before the patch. rich_text on ReviewRequest and on
ChangeDescription was false, when it was true on the draft.