Feature: Leverage/Integration with existing policy engines, like OPA

[4everming]

Is your feature request related to a problem? Please describe.
No

Describe the solution you'd like
Currently, Project Narrows is a policy-based(rule-based) system that helps users to identify violations and vulnerabilities.
OPA(Open Policy Agent) is a flexible, fine-grained control for administrators across the cloud-native stack.
We would like to leverage something like OPA to implement a declarative and loose-coupled policy from the services' code with a unified approach.