feat: Add libguestfs
To be able to set VM root password as per https://stackoverflow.com/a/54440564/96588 and https://github.com/NixOS/nixpkgs/issues/37540#issuecomment-675800010.
To be able to set VM root password as per https://stackoverflow.com/a/54440564/96588 and https://github.com/NixOS/nixpkgs/issues/37540#issuecomment-675800010.