Add RBAC tests for identity v3 application credentials API

This patchset adds RBAC tests for identity v3 application
credentials API [0], which enforces the following policies: [1].

[0] https://developer.openstack.org/api-ref/identity/v3/index.html#application-credentials
[1] https://github.com/openstack/keystone/blob/master/keystone/common/policies/application_credential.py

Change-Id: I986e245a0bf7c4c37089a4a2dae7d9067c74162b
2 files changed