[TASK] Implemented all_marker for mail templates

Classes/Service/MailTemplateService.php

@@ -332,6 +332,8 @@ class MailTemplateService {
 		/** @var StandaloneView $emailView */
 		$emailView = $this->objectManager->get(StandaloneView::class);
 		$emailView->assignMultiple($this->markers);
+		$emailView->assign('all_marker', $this->getAllMarker($this->markers));
+
 		if (NULL === $defaultTemplateContent) {
 			$emailView->setTemplateSource(\trim($template->getSubject()));
 			$subject = $emailView->render();
@@ -940,4 +942,26 @@ class MailTemplateService {
 	public function setSubject(string $subject) {
 		$this->subject = $subject;
 	}
+
+	/**
+	 * Get a single variable containing a list of all markers
+	 *
+	 * @param array $markers
+	 * @return string
+	 */
+	private function getAllMarker(array $markers) {
+		$allMarker = '';
+
+		foreach ($markers as $key => $value) {
+			if (!\is_array($value)) {
+				$allMarker .= $value . PHP_EOL;
+			} else {
+				foreach ($value as $innerKey => $innerValue) {
+					$allMarker .= $innerValue . PHP_EOL;
+				}
+			}
+		}
+
+		return $allMarker;
+	}
 }