- Add new Available trait
- Job now uses engine provided by get_engine function
- Use crun for podman if available
- Package crun for opensuse variants

- it's not implemented anyway

- use skopeo to copy image from registry to local directory
- on image cleanup remove directory

- CRun::is_available now checks for it's dependencies which we do
  not need if used through podman

Instead of relying outside dep check, move this check to
CRun::is_available.

Also add some debug logging.

- when using skopeo we need transport prefix, if there is non, use
  docker:// as default