Add RBAC test cases to manage cinder volume

Add test cases to test the following actions:
"volume_extension:volume_manage": "rule:admin_api",
"volume_extension:volume_unmanage": "rule:admin_api",

Change-Id: Ic47cb1638c0793d288f3dd40a3036aa50b4ab24a
Partially-Implements: blueprint "Add rbac tests for volume_manage_client"
1 file changed