Add hook_uuid_entities_pre_rebuild_alter()

UUID handles dependencies by creating required entities before their parent entities.
This doesn't work for field_collection which requires the host entity to be present for field_collection_item entities to be saved properly.

Because of this there needs to be a way to alter the list of entities before they are processed. I propose adding an alter hook to uuid_entities_rebuild(). This will allow field_collection to remove any field_collection entities from the list to add them back later in hook_field_uuid_presave().