Add VoxelPooling on CUDA

### Checklist

- [x] I have searched for [similar issues](https://github.com/isl-org/Open3D-ML/issues).
- [x] 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 `main` branch).

### Proposed new feature or change

I tried to perform `open3d.ml.torch.ops.voxel_pooling` or `open3d.ml.torch.layers.VoxelPooling` on CUDA.
However, "RuntimeError: VoxelPooling does not support CUDA" was displayed.
Please add support for VoxelPooling on CUDA.

### References

_No response_

### Additional information

_No response_