RBAC tests for os-extended-volumes policies

This commit adds RBAC tests for os-extended-volumes
policies, the documentation for which can be found here:

https://github.com/openstack/nova/blob/master/nova/policies/extended_volumes.py

Tests for both APIs that enforce each policy were added.

Change-Id: I6669f420743a3fee6470a7bb4ca5f1353a0e9696
Implements: blueprint rbac-tests-for-compute-extended-volumes
Depends-On: I1c14646dc8d102cd093be09833c23846781e5e73
diff --git a/releasenotes/notes/rbac-tests-for-compute-extended-volumes-7f3ccab122d22737.yaml b/releasenotes/notes/rbac-tests-for-compute-extended-volumes-7f3ccab122d22737.yaml
new file mode 100644
index 0000000..f7eb02d
--- /dev/null
+++ b/releasenotes/notes/rbac-tests-for-compute-extended-volumes-7f3ccab122d22737.yaml
@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Add RBAC tests for os-extended-volumes:volumes_attached policies, which
+    validate that "os-extended-volumes:volumes_attached" is returned in the
+    response body.