Add cron job for removing expired stored objects

Introduced `RemoveExpiredStoredObjectCronJob` to automate the deletion of expired stored objects every 7 days. Enhanced associated tests and updated relevant interfaces and classes to support the new cron job functionality.

src/Bundle/ChillDocStoreBundle/Repository/StoredObjectRepositoryInterface.php

@@ -17,4 +17,10 @@ use Doctrine\Persistence\ObjectRepository;
 /**
  * @extends ObjectRepository<StoredObject>
  */
-interface StoredObjectRepositoryInterface extends ObjectRepository {}
+interface StoredObjectRepositoryInterface extends ObjectRepository
+{
+    /**
+     * @return iterable<StoredObject>
+     */
+    public function findByExpired(\DateTimeImmutable $expiredAtDate): iterable;
+}