add list_opts to all modules with configuration options
add list_opts to all modules with configuration options

this allows these modules to be exposed as entry points, and consumed by
oslo-config-generator.

Co-Authored-By: Dolph Mathews <d00136b1f350cdfd4a4b13e2c189b3ba40c3257e@gmail.com>
Co-Authored-By: Ben Nemec <4bb9322d2721abaa797f20e8e3863e6a19240e0a@redhat.com>
Change-Id: I7f0ed83cc87a9647c341641134cefbb966d23bee
Closes-Bug: 1356438

citrix-openstack-build/oslo.policy,rodrigods/oslo.policy,openstack/oslo.policy