Security gates within MRs - Sync security report_approvers to pipeline security reports

What does this MR do?

• Add SyncReportApproverApprovalRules for copying project approval rules to merge requests (and deleting old)
• Add SyncSecurityReportsToReportApprovalRules for conditionally decrementing required_approvals to zero

This also includes some shims to the ApprovalRuleLike logic ensuring compatibility between the existing ApprovalProjectRule and ApprovalMergeRequestRule types

One of series of MRs to fully address #9928 (closed).

General checklist

• 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