Resolve miscellaneus accessibility issues in about:torconnect

There are a few issues in #41384 that have not been resolved yet:

1. Breadcrumbs being focusable.
2. Progress bar having no semantics.
3. Select group items having wrong semantics. Seems to have already been solved.
4. Location <form> is out of place.

I was going to address these along with other torconnect redesigns. But we don't have them in our roadmap, so I'll fix these issues for 16.0, so users don't have to wait another whole release for fixes.