Show edit pending comment button on mobile

What does this MR do and why?

• Shows Edit button on pending comments on mobile
• Top-aligns actions on mobile

Screenshots or screen recordings

Before	After

How to set up and validate locally

• Go to merge request
• Add a diff comment
• Start a review
• Size down screen

Links

• ✂️ UX Paper Cuts 17.1 → Wiki (#452225)