Request re-review from already assigned reviewer

Problem to Solve

After a reviewer has provided feedback on a merge request and an author has responded to that feedback, the reviewer needs to re-review the updates to make sure they meet the project standards and can be approved.

Currently, the only way to accomplish this would be requiring the reviewer to remove themselves and re-add them, or ping them in a comment inside of GitLab (or outside) to request this.

These are prone to error and unclear behavior on what the specific ask of the reviewer is.

Proposal

When reviewers are assigned, authors should have the ability to request a re-review of their contribution. This would provide a notification to the reviewer(s) via email and To-Do so that they know they need to look at a Merge Request again.