Implement secure RBAC for the l3 conntrack helper API
Implement secure RBAC for the l3 conntrack helper API

This commit updates the l3 conntrack helper 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: I0cabf79af61357e0a6f87f2444d27165a389319f

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