Move shared nvidia settings to a separate module

Reviewed-by: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>

m/module/nvidia.nix

@@ -0,0 +1,9 @@
+{ lib, config, ... }:
+{
+  # Configure Nvidia driver to use with CUDA
+  hardware.nvidia.package = config.boot.kernelPackages.nvidiaPackages.production;
+  hardware.nvidia.open = lib.mkDefault (builtins.abort "hardware.nvidia.open not set");
+  hardware.graphics.enable = true;
+  nixpkgs.config.nvidia.acceptLicense = true;
+  services.xserver.videoDrivers = [ "nvidia" ];
+}