Implement Policy Enforcer Plugin

- Added a new Policy Enforcer plugin to evaluate incoming messages against OPA policies.
- Configurable via YAML with options for policy sources, actions, and query.
- Integrated into existing configuration files for BAP and BPP.
- Updated related tests and documentation for the new functionality.
- Enhanced plugin manager to support Policy Enforcer instantiation.

install/docker-compose-adapter-beckn-one.yml

@@ -36,6 +36,7 @@ services:
     volumes:
       - ../config:/app/config
       - ../schemas:/app/schemas
+      - ../policies:/app/policies
     command: ["./server", "--config=/app/config/local-beckn-one-bap.yaml"]
 
   onix-bpp:
@@ -57,6 +58,7 @@ services:
     volumes:
       - ../config:/app/config
       - ../schemas:/app/schemas
+      - ../policies:/app/policies
     command: ["./server", "--config=/app/config/local-beckn-one-bpp.yaml"]
 
   sandbox-bap: