Save the date when a webauthn key was used last time for 2 factor authentication and show it in user settings

templates/helper.twig

@@ -230,4 +230,12 @@
         {% endfor %}
         </tbody>
     </table>
-{% endmacro parameters_table %}
+{% endmacro parameters_table %}
+
+{% macro format_date_nullable(datetime) %}
+    {% if datetime is null %}
+        <i>{% trans %}datetime.never{% endtrans %}</i>
+    {% else %}
+        {{ datetime|format_datetime }}
+    {% endif %}
+{% endmacro %}