osbuild scripts

[Eric Curtin]

We must write osbuild stages for ostree-based hosts and nonostree-based hosts.

We also must ensure this works with Android Bootloaders and UEFI+grub variants. So the test matrix at least initially should be 4, 2x2:

https://gitlab.com/CentOS/automotive/sample-images/-/tree/main/osbuild-manifests

The Automotive SIG repos is a good place to test these osbuild stages.

Note we have to run dracut twice, once for the mini initramfs and one for the larger initoverlayfs, similar to what is done in this shell script:

https://github.com/ericcurtin/initoverlayfs/blob/main/initoverlayfs-install