Use security policy read model for approval_rules

Why are we doing this work

As a part of this issue we want to start creating/updating/deleting approval_project_rules and approval_merge_request_rules when a security policy is changed. We also want to use the read model (approval_policy_rules) to sync approvals in MR.

Relevant links

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

Verification steps