Add push rules to audit events
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=8083)
</details>
<!--IssueSummary end-->
As part of audit events, we should log all instance-level changes in the admin panel.
We should track additions/changes to push rules on an instance:
1. Restriction toggles
1. Committer restriction
1. Reject unsigned commits
1. Do not allow users to remove git tags with git push
1. Check whether author is a GitLab user
1. Prevent committing secrets to Git
1. Commit message
1. Branch name
1. Commit author email
1. Prohibited file names
1. Max file size
issue