services: move .nix files into their own dirs

modules/services/pipewire/module.nix

@@ -0,0 +1,18 @@
+{
+  config,
+  lib,
+  ...
+}: let
+  cfg = config.modules.system.sound;
+  inherit (lib.modules) mkIf;
+in {
+  config = mkIf cfg.enable {
+    services.pulseaudio.enable = false;
+    services.pipewire = {
+      enable = true;
+      alsa.enable = true; # TODO Do I need this?
+      pulse.enable = true;
+    };
+    security.rtkit.enable = true;
+  };
+}