Remove ability to make multiple rapid PREreviews

[murkatr]

Here I posted two separate rapid PREreviews - one under my anonymous profile and one under my public profile and they both showed up as anonymous with two separate entries.

We want to make sure users can only submit one rapid PREreview and one full PREreview per preprint.

[thewilkybarkid]

I can recreate this locally. There's two things to look at:

1. The API needs to reject the second request.
2. The frontend needs to not display the form the second time.

The former's probably easier to start with, and will break the frontend's form (so at least there won't be duplicates).

[murkatr]

Sounds like a great plan! I am interested in keeping my public rapid PREreview entry if possible, no worries if not.