How to integrate multiple point clouds into VoxelBlockGrid for later mesh extraction

### 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](https://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](https://www.open3d.org/docs/release/) and the [latest documentation](https://www.open3d.org/docs/latest/) (for `main` branch).

### Proposed new feature or change

After discussing with several knowledgable people in Open3D, we did not find a way to integrate multiple point clouds in a VoxelBlockGrid. The VoxelBlockGrid seems to support only RGB-D images at the moment.
The aim is to extract a mesh using marching cubes.
Is there any way to do this?

### References

In the following issue:
https://github.com/isl-org/Open3D/issues/4515
people suggest to use the VoxelBlockGrid.
But unfortunately it does not support the use case.

### Additional information

_No response_