How to set contraint on transformation matrix?

### 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

I am working on a problem where all point clouds have their vertical axis aligned, e.g., the z-axis of all point clouds are the same. I want to apply point cloud registration on them. I know that the rotation matrix of the transformation should be a rotation around the z-axis. Thus, I want to set a constraint on the transformation matrix so that the resulting rotation matrix of registration is exactly a rotation around the z-axis. I do not want the algorithm to search for the rotation matrix among all available matrices. I wonder whether there is any implementation so that I cant put this constraint when I want to register the point clouds.