Implement secure RBAC for quotas API
Implement secure RBAC for quotas API

This commit updates the quotas policies 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: Id21f81bb9f550a576d93498db62400af48aaf43a

mahak/neutron,mahak/neutron,openstack/neutron,openstack/neutron,mahak/neutron,openstack/neutron