[xpadneo] Moved to it's own config. Adds an env var for steam.

system/features/bluetooth.nix

@@ -1,6 +1,9 @@
 { pkgs, ... }:
 {
+  # Enable bluetooth.
+  hardware.bluetooth.enable = true;
 
+  # Install the management service and packages.
   environment.systemPackages = with pkgs; [
     bluez
   ];