Export referenced entities by layout section field

Problem/Motivation

Layout builder serialized only configuration.
See https://www.drupal.org/project/drupal/issues/2942975
Example

                        "uuid": "c745e4e9-39e2-4c60-b85e-8c1b2708f709",
                        "region": "1",
                        "configuration": {
                            "id": "inline_block:default_block",
                            "label": "test",
                            "provider": "layout_builder",
                            "label_display": "visible",
                            "view_mode": "full",
                            "block_revision_id": "13",
                            "block_serialized": null,
                            "context_mapping": [],
                            "type": "default_block",
                            "uuid": "b26701df-382a-40a0-ad08-c1e1a2beba24"
                        },
                        "additional": [],
                        "weight": -8

I think we need export referenced entities.

Steps to reproduce

1. Enable Layout Builder and Devel modules
2. Turn on "Use Layout Builder" and " Allow each page to have its layout customized." options in 'Page' node type display settings.
3. Create node with some content, add some blocks in "Layout" tab.
4. Export this node using drush dcder node --entity_id=1
Does't export block entities

Proposed resolution

1. Create service for get all referenced entities by layout section field.
2. Use service in `\Drupal\default_content_deploy\Exporter::getEntityReferencesRecursive` method.
3. Export this node using drush dcder node --entity_id=1