Make issues list keyboard accessible
What does this MR do and why?
- Makes comments counter and confidential icon keyboard-accessible
- Move reused button classes into method
What does this MR not do?
There might be more metadata attributes I don't currently have on my screen; if they're not keyboard-accessible in this MR I'll do it separately!
Screenshots or screen recordings
| Before | After |
|---|---|
| Not keyboard accessible |  |
| Not keyboard accessible |  |
How to set up and validate locally
Go to issues list (ie http://gdk.test:3000/gitlab-org/gitlab-test/-/issues)