Feature Request: Add MR approval settings change as a webhook event

Proposal

The webhook events are mentioned in https://docs.gitlab.com/ee/user/project/integrations/webhook_events.html.

It would be great if there was a webhook event trigger for changes in project/group settings. In our case, specifically the MR approval settings. This would be a great addition for hardening projects against changes made by developers/maintainers to push their code in. This would be very useful for audits.

MR approval settings are documented in https://docs.gitlab.com/ee/user/project/merge_requests/approvals/settings.html.

A change in the MR approval settings would trigger a webhook event. The webhook event would list the name of the change, some details of the change, the author of the change, the timestamp, etc.

This would help us to harden the project/group as if changes are detected in the settings, a job can be configured to revert the changes immediately.