Render IP map and host maps according to network_data.yaml

Render IP map and host maps according to network_data.yaml

This change renders the network IP maps and hostname maps for
all networks defined in network_data.yaml. This should make it
possible to create custom networks that will be rendered for
all applicable roles.

Note that at this time all networks will be rendered whether
they are enabled or not. All networks will be present in all
roles, but ports will be associated with noop.yaml in roles
that do not use the network. This is in accordance with
previous behavior, although we may wish to change this in
the future to limit the size of the role definitions and
reduce the number of placeholder resources in deployments
with many networks.

Note that this patch is a replacement for original patch
https://review.openstack.org/#/c/486280, which I was having
trouble rebasing to current.

Change-Id: I445b008fc1240af57c2b76a5dbb6c751a05b7a2a
Depends-on: I662e8d0b3737c7807d18c8917bfce1e25baa3d8a
Partially-implements: blueprint composable-networks