Web-app: Improve visibility of an accepted "save code now request" on submission

When submitting a request the text appears on the page under the form

The "save code now" request has been accepted and will be processed as soon as possible.

Personally I didn't see it at first and didn't know if I should re-submit. I think it can be improved with a more fun design.

---

Migrated from T1288 (view on Phabricator)