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/components/falukant/MessagesDialog.vue

@@ -11,7 +11,7 @@
   >
     <ul class="messages">
       <li v-for="n in messages" :key="n.id" :class="{ unread: !n.shown }">
-        <div class="body">{{ $t(n.tr) }}</div>
+        <div class="body">{{ $t('falukant.notifications.' + n.tr) }}</div>
         <div class="footer">
           <span>{{ formatDate(n.createdAt) }}</span>
         </div>