Submission Page reorg final touches

[rakshanaj17]

• [x] Display URL update - will need to return display URL in response
• [x] Make new mention, need logic for state change (currently needs page refresh)
• [x] Webpage community logo cut off (UI fix)
• [x] State update for anonymous/non-anonymous changes, doesn't change in real-time (need refresh)
• [x] Cancelling a change of description/title appears to still render it, but refreshing removes it
• [x] Saving a submission without a source URL temporarily makes the URL field blank (until refresh)
• [x] Saving hashtag in title does not reflect hashtag on save unless page is refreshed
• [x] Mention reverts to original description on suggestion click
• [x] When error, display the backend error message to help the user fix whatever they did wrong instead of "could not save changes"
• [x] Spellcheck

[rakshanaj17]

fixed

[rakshanaj17]

(4) -> do you mean updating username in "Submitted by"?