Ship with nix-info to facilitate bug reporting, record other debug info

[madeline-os]

nixpkgs asks users to run nix-shell -p nix-info --run "nix-info -m" when filing a bug report. Since obelisk is a multi-platform development environment, we really need this information to efficiently process bug reports. We can have an ob debug subcommand for getting info like this. I'm not sure what we would like beyond the info in nix-info.

One thing that comes to mind is binary cache configuration.