Update localization for notifications in English and German

- Added new notification translations for election creation in both `falukant.json` files.
- Updated the message rendering in `MessagesDialog.vue` to include the new translation structure.

frontend/src/i18n/locales/de/falukant.json

@@ -14,6 +14,9 @@
             "tooltip": "Nachrichten",
             "empty": "Keine Nachrichten vorhanden."
         },
+        "notifications": {
+            "notify_election_created": "Es wurde eine neue Wahl ausgeschrieben."
+        },
         "health": {
             "amazing": "Super",
             "good": "Gut",