Description of feature:
- As a reviewer/project maintainer I want to add review status tags, such as "Changes requested" to a PR when I review it.
- As a reviewer/project maintainer I want to be able to see these tags in the list of PRs.
- As an author of a PR, I want to be able to remove the tag "Changes requested" after I implemented the requested changes (author of the PR does not have any special priviledges/ roles in the project).

Notes:
- This may be implemented as special tags to the PR (review status tags). The author of PR and the reviewers would be able to add/remove these tags.