linux: provide a nix package in flake.nix

[alicelogos]

Would it be possible to provide a Nix package for Sourcegraph App in flake.nix?

I think it may be something like this:

packages = genAttrs defaultSystems (system: {
    sourcegraph-app = ...;
  }
);

# and optional
apps = genAttrs defaultSystems (system: {
    sourcegraph-app = {
      type = "app";
      program = "${self.packages.${system}.sourcegraph-app}/bin/sourcegraph";
    };
  }
);

Then one can run the app with just one command:

nix run github:sourcegraph/sourcegraph#sourcegraph-app