AS | Refactor the policy module

[Xynnn007]

This PR mainly includes the following work

• Replace golang OPA with regorus in CoCo AS.
• Add some documents for the policy of CoCo AS.
• Some refactoring for policy management, mainly for user-friendly
• Make SNP's runtime data check optional for CoCoAS, which is enforced when the requester is KBS.

I also did some performance test with SNP evidence check. After replacing golang OPA with regorus, the throughput was increased by approximately 200%.

cc @jialez0

[ChengyuZhu6]

Nice patch!