Returns a bound display entity by binding a layout to this unbound display.
This will DisplayInterface::mapBlocksToLayout() using the provided layout, then create and return a new Display object with the output. This is just a factory - calling code is responsible for saving the returned object.
\Drupal\layout\Plugin\LayoutInterface $layout: The desired layout.
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\BoundDisplayInterface.
\Drupal\layout\Config\BoundDisplayInterface The newly created entity.
public function generateDisplay(LayoutInterface $layout, $id, $entity_type = 'display');