FIX: prevents playing chat sound when in DnD (#19575)

I couldn't figure a sane way to test this, I'm open to suggestions.

plugins/chat/assets/javascripts/discourse/initializers/chat-audio.js

@@ -19,6 +19,10 @@ export default {
 
     withPluginApi("0.12.1", (api) => {
       api.registerDesktopNotificationHandler((data, siteSettings, user) => {
+        if (user.isInDoNotDisturb()) {
+          return;
+        }
+
         if (!user.chat_sound) {
           return;
         }