What would you like to be added:
A new API to support E/W Authorization.

Why this is needed:

East/West (E/W) authorization is a critical part of any service mesh. To ensure GAMMA can be used as a standalone solution by a broad user base, it must include some form of E/W authorization.

Most (if not all) meshes today provide this functionality, some examples:

• Istio - https://istio.io/latest/docs/reference/config/security/authorization-policy/
• Linkerd - https://linkerd.io/2-edge/reference/authorization-policy/
• Kuma - https://docs.konghq.com/mesh/latest/policies/meshtrafficpermission/