Ignition support in Fedora CoreOS is now mature and less likely to drastically change. Let's split all the units, config, services, etc. in an ignition RPM sub-package.

This would let us more easily include Ignition support in Project Sagano images: https://gitlab.com/CentOS/cloud/sagano

This will also enable us to de-duplicate the effort with https://github.com/fedora-iot/ignition-edge.

To reduce the impact on development speed, we would enable CI in the new repo and add auto-packaging updates with packit for the Fedora package.

Upstream issue: https://github.com/coreos/fedora-coreos-tracker/issues/1582