* add(ci): install `cargo-make` through `nix`
Should speed the e2e tests up by about 2 minutes.
Can easily reverted by `commenting/uncommenting`
the `run` part of the `Install cargo-make` step.
* check if cachix speeds the process up
* add(nix): add crate2nix
To have a better experience on ci, due to improved caching
of dependencies. Also organize file hierarchy slightly.
* ci(nix): manually check a default system
Is needed because `nix flake check` accidentally tries to build IFD.
