[BUGFIX] Fix adding of the marker name in new registerd forms

Classes/XClass/Form/FormEditorController.php

@@ -170,7 +170,7 @@ class FormEditorController extends \TYPO3\CMS\Form\Controller\FormEditorControll
 			}
 
 			$markers[] = [
-				'marker' => $markerName,
+				'identifier' => $markerName,
 				'type' => MailTemplateService::MARKER_TYPE_STRING,
 				'value' => $element['label'],
 				'description' => $element['label']