Approval & Unapproval Webhooks

What does this MR do?

This adds a new webhook action to merge requests. Currently the "Approved" and "Unapproved" webhooks only fire if the approvals required threshold is met. My current issue is that we have 5+ approvals required on some MR and can take 1-2 weeks to review, I have setup the system to trigger a "approval" webhook action on each approval leading up to the minimum threshold. Once the threshold is met a "approved" action is sent. The same happens in reverse for unapprovals with a "unapproved" and "unapproval" actions.

What are the relevant issue numbers?

N/A

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?
• Security reports checked/validated by reviewer