Is there any way of adding label values to the ScalableTSDFVolume voxels?

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

Is there any way of adding label values to the ScalableTSDFVolume voxels? if not supported, is there any way of achieving this?
That would useful to store the semantics of points.