Nixify the workflow

[aeryz]

I manually run the build commands, image creation, run kernel stuff from my history. We should nixify all of these.

[aeryz]

One TBD here is, how crazy do we wanna go with the vsfs-tool support. So, the tool itself supports providing the file layout as a json. So we could technically write a nix derivation where you can specify file paths and the binaries. We can easily and reproducably create the image every time we run the kernel easily.