Returns an entity with the non-layout-specific configuration of this one.
string $id: The entity id to assign to the newly created entity.
string $entity_type: The type of entity to create. The PHP class for this entity type must implement \Drupal\layout\Config\UnboundDisplayInterface.
\Drupal\layout\Config\UnboundDisplayInterface The newly-created unbound display.
public function generateUnboundDisplay($id, $entity_type = 'unbound_display');