Add translation strings for toasts, update data load toasts to use generic failed to load data message

client/pages/config/notifications.vue

@@ -142,7 +142,7 @@ export default {
       this.loading = true
       const notificationResponse = await this.$axios.$get('/api/notifications').catch((error) => {
         console.error('Failed to get notification settings', error)
-        this.$toast.error('Failed to load notification settings')
+        this.$toast.error(this.$strings.ToastFailedToLoadData)
         return null
       })
       this.loading = false
@@ -172,4 +172,4 @@ export default {
     this.$root.socket.off('notifications_updated', this.notificationsUpdated)
   }
 }
-</script>
+</script>