Motivation for this change

Added it as it was painful to package, but I've since felt like it shouldn't be in nixpkgs.

It's a hack to essentially treat pypi like a binary package installer... instead of doing a command -v dotnet || echo "please install dotnet" to check if it's needed.

Outdated, and new package isn't trivial to package anymore.
Not really useful outside of Azure Machine Learning anyway.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.