Add Tensor FPFH

[yuecideng]

This PR adds tensor ComputeFPFHFeature and use bunny mesh for unit test.

This change is 

[update-docs]

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

[theNded]

Reviewed 13 of 15 files at r1, 6 of 6 files at r2, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @reyanshsolis, @ssheorey, @yuecideng, and @yxlao)

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.clang-format line 5 at r2 (raw file):

ColumnLimit: 80
UseTab: Never
# Standard: c++14

Is this change necessary? It affects formatting.

[yuecideng]

It was changed probably when I tried to fix the formatting issue in my PC. I will remove it anyway... @theNded

[theNded]

Would you please also attach the benchmark log in this PR for reference?

@reyanshsolis would you please create a following PR on matching tensor FPFH using the tensor nns interface, if you have any bandwidth?
I also notice nns does not have pybind as of now if I understand correctly. Would this be an obstacle to implementation?

Reviewed 4 of 4 files at r3, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @reyanshsolis, @ssheorey, @yuecideng, and @yxlao)

[yuecideng]

Update

The parameters of nns search is sensitive to the time cost of comuputing fpfh with tensor API. We should avoid using large max_nn on tensor cuda. @theNded @reyanshsolis

[yxlao]

Reviewed 1 of 15 files at r1, 1 of 6 files at r2, 1 of 4 files at r3, 4 of 4 files at r4, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @reyanshsolis, @ssheorey, and @yuecideng)