Migrate header components in tags and compare revisions

What does this MR do and why?

• Migrates header components in:
  • New tag
  • Compare revisions
• Fix mobile Swap button (not currently working on prod)
• Removes CSS in favor of utility classes
• Use tailwind classes

Screenshots or screen recordings

Before	After

How to set up and validate locally

• New tag --> http://127.0.0.1:3000/gitlab-org/gitlab-test/-/tags/new
• Compare --> http://127.0.0.1:3000/gitlab-org/gitlab-test/-/compare?from=master&to=master

Links

• ✂️ UX Paper Cuts 17.3 → Dark mode - Design Support (#452231 - closed)