Integrate with core's default content exporter

Problem/Motivation

As of Drupal 11.3, core has the ability to export default content (i.e., for creating recipes). Its API is pretty robust, and extensible, and we need to integrate with it. For crops, that means two things:

• The entity that the crop references, if it's a content entity, needs to be marked as a dependency of the crop.
• The entity_id field has to be converted to a UUID upon export, and then resolved back to a serial ID upon import.