Add normal related functions to PointCloud and TriangleMesh

[yuecideng]

1. Add NormalizeNormals for both Tensor PointCloud and TriangleMesh.
2. Add normal orientation functions for Tensor PointCloud.
3. Add triangle and vertex normals computation for Tensor TriangleMesh.

This change is 

[update-docs[bot]]

Thanks for submitting this pull request! The maintainers of this repository would appreciate if you could update the CHANGELOG.md based on your changes.

[yuecideng]

Sure, I will test it and update.

Update:

I use ArmadilloMesh to test the performance of vertex and triangle normals computation with and without normalization. The reuslts are as follow: With normalization:

Without normalization:

The new tensor implementation is not good in CPU. I also test the performce of two normals orientation fucntions for PointCloud:

I think it would be better to implement these functions in kernel currently @reyanshsolis @yxlao

[yuecideng]

By implementing these fucntions in kernel, the performance has lots of gain: With normalization:

PointCloud functions: