vscode: switch to unfree, binary package

[mucaho]

Motivation:

As described in #14354, the current vscode derivation fails to build on hydra, due to the expression depending on npm install.
There are a lot nodePackage dependencies that are missing in the nixpkgs collection (some of them must be natively build). I guess that would take quite some effort to get vscode to successfully build from source.
Hence, this PR switches the drv to use the unfree, pre-built binary and patchElf it accordingly. That could be changed in future of course.

Questions:

I don't have a Mac to test this, how does the binary find the shared libraries on a darwin architecture? AFAIU, patchELF only works on linux platforms. Should I remove darwin as a build target for this derivation?

Things done:

• Tested using buildtime sandboxing (nix-build . --option build-use-chroot true -A vscode)
• Tested using runtime sandboxing (nix-shell -I nixpkgs=. --pure -p vscode)
• Built on platform(s)
  • NixOS
  • OS X
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip" from root of nixpkgs fork
  • dependent pkg vscode compiles & runs
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

More

Fixes issue #14354

[mention-bot]

By analyzing the blame information on this pull request, we identified @fluffynukeit, @vcunat and @gebner to be potential reviewers

[jgillich]

👍 Works for me, while the current package doesn't even build (due to chroot I suppose).

@vcunat