We no longer require any user intervention when testing dracut on
a local block device in qemu, assuming everything passes. If things fail,
we still might need to manually kill things.
This creates a basic root filesystem, creates an initramfs, and tries
to boot to the basic filesystem.
The init code on the test filesystem prints how much memory is used vs. free
and then drops to a shell. Exiting the shell will power off the VM.