Add post-update hook

Closes #3520833

layout_builder_st.post_update.php

+<?php
+
+/**
+ * @file
+ * Contains post-update hooks for layout_builder_st.
+ */
+
+declare(strict_types=1);
+
+/**
+ * Rebuilds the container for updating layout_builder_st to v2.0.0.
+ */
+function layout_builder_st_post_update_rebuild_container_for_v2(): void {
+  // Empty post-update hook to force a container rebuild.
+}