- Add a visual (but still semantic way) separation between Forgejo's
generated attachments and the user's uploaded ones.
- The styling was first done by `ul` element, but is moved to the
individual list items to have better control over them.
- Add tooltip explaining the attachment was generated by Forgejo.
- Remove the tooltip of the other attachments and 'simplify' them into a text.
- Resolves#2893
Co-authored-by: 0ko <0ko@noreply.codeberg.org>
(cherry picked from commit 20a3597220)