Better flow for PR reviewers

[moniuch]

I think GItLens does a great job while providing a flow-oriented approach to PRs for the author. It could still do better for reviewers.

My dream solution would be that there be a section REVIEWS where one would find all the PRs in focus. In focus - meaning not all the open PRs that are currently in the repo, but those where I was a commenter or reviewer, or just deliberately chose to be following.

Some key features:

0. As per user settings, I could get notified of new PRs as they come in, or if I am among CODEOWNERS
1. I should also be able to quickly add a followed PR just by pasting its url or selecting it from a list of opened and most recent
2. All the ongoing discussions in the focused PRs and resolved changes should produce graphic notifications (bold, unread dot, etc)
3. PRs that have been merged, should be archived or deleted (as per user settings). And the associated local branch should be deleted as well (as per users settings)
4. Each PR should have an action named alongside Pull and review which would pull the branch or update it (forcibly if --force was used by the author)
5. When checking out the PR branch it'd be awesome to first remember all opened tabs, so that when I'm done with my review, I could easily return to my workspace as I left it.

Possibly more ideas will come to mind, in which case I will update this ticket.