bede782630
policy-in-code will be supported by the main neutron repo because the neutron API layer uses the policy code in the neutron repo. However, neutron_lib.context refers to its own policy enforcer, so we need a small code to support policy-in-code in neutron-lib side. Part of blueprint get-policy-from-neutron-lib Change-Id: I4923a069f4080dc53a8fb359f5a1518de06feb2f