build NixOS VM on darwin

[a2not]

left in #6 as TODO

https://github.com/nixos-lima/nixos-lima/tree/master?tab=readme-ov-file#building-and-testing-the-system-image

[a2not]

lots of todos in Makefile
https://github.com/a2not/dotfiles/pull/6/files

[a2not]

big step forward
7a5394a

---

TODO: needs linux-builder or nix-rosetta-builder to build
https://github.com/nixos-lima/nixos-lima/blob/master/README.md#prerequisites

$ make img
...
error: a 'aarch64-linux' with features {} is required to build '/nix/store/xxxxxxxx-X-Restart-Triggers-dhcpcd.drv', but I am a 'aarch64-darwin' with features {apple-virt, benchmark, big-parallel, nixos-test}