Give project selection dropdowns responsive width, long names wrap.

What does this MR do?

Makes two dropdown menus (branch name selector & project selector) wider on larger screens, and allows their contents to wrap.

Are there points in the code the reviewer needs to double check?

Sanity check.

Why was this MR needed?

Considered a regression, as users who relied on long branch names could no longer see them fully.

Screenshots (if relevant)

Before:

After:

After (updated after fixes, including project selector):

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #15633 (closed)