nixos-rebuild: restore local sudo functionality

This functionality used to exist and was then removed in #331741. The
issue was that $SUDO_USER is already used by `sudo` as an environment
variable.

This change makes it possible to checkout a flake repository, as a user,
enter the devshell, and with the additions below and apply changes with
`nixos-rebuild switch`.

```nix
{ pkgs }:
let
  nixos-rebuild = pkgs.writeShellApplication {
    name = "nixos-rebuild";
    runtimeInputs = [ pkgs.nixos-rebuild ];
    text = ''
      set -euo pipefail
      exec nixos-rebuild --flake "$PRJ_ROOT" --use-local-sudo "$@"
    '';
  };
in
pkgs.mkShellNoCC {
  packages = [
    nixos-rebuild
  ];

  shellHook = ''
    export PRJ_ROOT=$PWD
  '';
}
```

0 files changed, 0 insertions, 0 deletions