Add `Settings` type

js/modules/types/settings.js

@@ -0,0 +1,4 @@
+const OS = require('../os');
+
+exports.shouldShowAudioNotificationSetting = () =>
+  !OS.isLinux();

preload.js

@@ -106,6 +106,7 @@
   window.Signal.Types.Attachment = require('./js/modules/types/attachment');
   window.Signal.Types.Message = require('./js/modules/types/message');
   window.Signal.Types.MIME = require('./js/modules/types/mime');
+  window.Signal.Types.Settings = require('./js/modules/types/settings');
 
   // We pull this in last, because the native module involved appears to be sensitive to
   //   /tmp mounted as noexec on Linux.