Move audio configuration into a service module

- Move audio configuration into a service module to make it easily
  usable by multiple hosts.
- Allow configuration of AirPlay 2 name.
- Don't set MQTT topic of Shairport-Sync (AirPlay 2) explictly. Defaults
  to hostname now.
- Don't set sound.enable anymore, since its not needed.

config/hosts/audio/audio.nix

@@ -0,0 +1,13 @@
+{ pkgs, ... }:
+{
+  imports = [
+    ../../../modules/services/audio
+  ];
+
+  ccchh.services.audio = {
+    enable = true;
+    name = "Audio";
+  };
+
+  users.users.chaos.extraGroups = [ "pipewire" ];
+}