* Allow empty string to clear URL-type DB fields.
- To address difficulties with clearing URL-type fields like
avatars, banners, site icons, this PR turns the URL type form
fields into strings.
- This allows an empty string to be used as a "clear data", as
in the case with the regular text form fields.
- Also includes various cleanups.
- Fixes#4777
- Context: #2287
* Fixing comment.
* Use Option<&str> and deref.
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Co-authored-by: SleeplessOne1917 <28871516+SleeplessOne1917@users.noreply.github.com>