kernel command line support for qemu and cloud-hypervisor

[rinor]

#1983 already added support for firecracker

For context, after reading https://www.linkedin.com/pulse/podman-executing-unikernels-luigi-zuccarelli-fh41f/ and some of the comments there, decided to check and play a bit around with the idea.

Using as base one of the mentioned shims there, started a test repo to integrate nanos - https://github.com/rinor/nrunc and need support for kernel command line on both qemu and cloud-hypervisor to enable network configuration for nanos images on that default setup.