feat(validators): add date validation method

- Implemented date validation using DateTime::createFromFormat
- Supports both 'Y-m-d\TH:i:s.v\Z' and ATOM formats
- Returns boolean indicating if value is valid date

Signed-off-by: bahman <bja@adlas.at>

Author: bahman

lib/Validators/BaseValidator.php

@@ -107,6 +107,16 @@ private function not_empty($value): bool {
 		return !empty($value);
 	}
 
+	/**
+	 * @param $value
+	 * @return bool
+	 */
+	private function date(string $value): bool {
+		$date = \DateTime::createFromFormat('Y-m-d\TH:i:s.v\Z', $value)
+			?: \DateTime::createFromFormat(\DateTime::ATOM, $value);
+		return $date !== false;
+	}
+
 	/**
 	 * @throws Exception
 	 */