release: add basic cloudinit images

[bapt]

Summary

Provide both zfs and ufs images which a 1MB partition reserved for the
config drive wearing a GPT Label "config-drive" to allow consumer to
know where they should push the config drive on the provided image.

2 formats available: qcow2 and raw

This has been tested on OVHCloud baremetal via "bring your own image"
Also tested on openstack

Sponsored by: OVHCloud

[emaste]

I'd like to reduce the duplication in the cloud image *.conf files but that's not specific to this addition.