Add StoredObjectPointInTime entity and related functionality

Implemented a new StoredObjectPointInTime entity to manage snapshots of stored objects. This includes related migrations, enum for reasons, repository, and integration with StoredObjectVersion.

src/Bundle/ChillDocStoreBundle/Entity/StoredObjectPointInTimeReasonEnum.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * Chill is a software for social workers
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Chill\DocStoreBundle\Entity;
+
+enum StoredObjectPointInTimeReasonEnum: string
+{
+    case KEEP_BEFORE_CONVERSION = 'keep-before-conversion';
+    case KEEP_BY_USER = 'keep-by-user';
+}