Allow approval after in-UI rebase or non-fast-forward merge commit

Problem to Solve

If you have the Prevent approval of merge requests by merge request committers setting turned on and a person performs an in-UI rebase or merge, that person is no longer eligible as an approver.

Example: a branch is behind its target, there's UI to rebase, a person clicks that button, their approval is revoked because they're not allowed to both commit and approve.

Would it be desirable to allow certain actions to not count as "a committer" like doing a non-fast-forward merge commit or rebase through the UI?

Proposal

Rebase actions performed via the UI (rebase button or /rebase) quick action should be excluded from the checks that prevent people from approving and then merging an MR.

Testing

Add/update test in spec/features to check approval can still be given after Ui rebase. Most likely: spec/support/shared_examples/quick_actions/merge_request/rebase_quick_action_shared_examples.rb SET: @jay_mccure