Show remaining approvals in merge requests

Problem description

MRs in gitlab-org/gitlab often require many approvals. As a maintainer keeping track of this to know when a MR can be merged is difficult.

Current behaviour

Our approval rules doesn't remedy this as it only needs 1 approval and the rest of the files are optional.

I've created MRs that require up to 8 approvals and in those cases I keep track of the approvals in a the MR description using checkboxes:

Suggested solution

@terrichu suggested in a comment that we add this to dangerbot and I think that's a good idea. I'm not 100% sure how to do that for gitlab-org/gitlab, but I have some ideas:

1. Add checkboxes to the Reviewer roulette comment suggestions.
2. Add a dedicated comment that looks similar to the screenshot above.
3. Dynamically add a Approvals section to the bottom of the MR description based on labels / reviewer roulette.