Implement secure RBAC for quotas
Implement secure RBAC for quotas

This commit updates the policies for quotas to understand scope checking and
account for a read-only role. This is part of a broader series of changes
across OpenStack to provide a consistent RBAC experience and improve security.

Change-Id: Id3f3192fb9948f71b0b9cb03d2ef8ffd0b770620

openstack/manila,openstack/manila