[nix] Cleans up warnings about options and reduces duplication

system/features/audio.nix

@@ -0,0 +1,16 @@
+{ ... }: {
+  # RealtimeKit hands out realtime scheduling priority to user processes on
+  # demand, e.g. audio
+  security.rtkit.enable = true;
+
+  # Enable sound with pipewire.
+  services.pulseaudio.enable = false;
+  services.pipewire = {
+    enable = true;
+    alsa.enable = true;
+    alsa.support32Bit = true;
+    pulse.enable = true;
+    # If you want to use JACK applications, uncomment this
+    #jack.enable = true;
+  };
+}