This is an improvement of the clanTest nixos vm test module.
The module now has a new option clan.test.fromFlake that allows to specify a flake.nix as the source for the test clan instead of specifying clan.XXX options.
This in turn allows accessing the `flake.nix` inside the test driver allowing to use the clan cli on it
We want each machine not only to be exposed via nixosConfigurations but also as a module.
This allows re-importing the machine in tests and override the architecture for example.
