bringToFront method
Moves an object to the front of z order.
Implementation
bool bringToFront(String id) {
final index = _objects.indexWhere((object) => object.id == id);
if (index < 0 || index == _objects.length - 1) return false;
_remember();
final object = _objects.removeAt(index);
_objects.add(object);
render();
_emitChange();
return true;
}