dispose method
Fully dipose of all the the resouces managed by the annotation manager. The manager cannot be used after this has been called
Implementation
Future<void> dispose() async {
_idToAnnotation.clear();
await _setAll();
for (var i = 0; i < allLayerProperties.length; i++) {
await controller.removeLayer(_makeLayerId(i));
await controller.removeSource(_makeLayerId(i));
}
}