Federation: Add task for setting up placement policies (#4075)

* Add task for setting up placement policies

* Update version of management sidecar in policy engine deployment

* Address @nikhiljindal's comments

- Lower case filenames
- Comments in policy
- Typo fixes
- Removed type LoadBalancer from OPA Service

* Add example that sets cluster selector

Per-@nikhiljindal's suggestion

* Fix wording and templating per @chenopis

docs/tasks/federation/policy-engine-service.yaml

@@ -0,0 +1,13 @@
+kind: Service
+apiVersion: v1
+metadata:
+  name: opa
+  namespace: federation-system
+spec:
+  selector:
+    app: opa
+  ports:
+  - name: http
+    protocol: TCP
+    port: 8181
+    targetPort: 8181