✨(frontend) introduce a notification settings

I extended Room settings with a new tab, allowing users to toggle
the sound notification they want.

Their choices will be persisted.

src/frontend/src/locales/de/settings.json

@@ -19,6 +19,19 @@
     },
     "permissionsRequired": ""
   },
+  "notifications": {
+    "heading": "",
+    "label": "",
+    "actions": {
+      "disable": "",
+      "enable": ""
+    },
+    "items": {
+      "participantJoined": "",
+      "handRaised": "",
+      "messageReceived": ""
+    }
+  },
   "dialog": {
     "heading": ""
   },
@@ -30,6 +43,7 @@
   "tabs": {
     "account": "",
     "audio": "",
-    "general": ""
+    "general": "",
+    "notifications": ""
   }
 }