Creates a duplicate of the EntityDisplay object on a different view mode.
The new object necessarily has the same $targetEntityType and $bundle properties than the original one.
$view_mode: The view mode for the new object.
\Drupal\entity\Plugin\Core\Entity\EntityDisplay The new object.
Overrides EntityDisplayBaseInterface::createCopy
public function createCopy($mode) {
$display = $this
->createDuplicate();
$display->mode = $display->originalMode = $mode;
return $display;
}