Following the integration in FCOS, and to bring us closer to Image Mode RHEL, we should integrate composefs in RHCOS and enable it by default.

The main integration point to look at is around the interaction with kdump.

See:

• https://github.com/coreos/fedora-coreos-tracker/issues/1718
• https://docs.fedoraproject.org/en-US/fedora-coreos/composefs/
• https://github.com/rhkdump/kdump-utils/pull/28
• https://bugzilla.redhat.com/show_bug.cgi?id=2284097

We will need documentation for this feature.