[Backend] Integrate Paddle to ml module

[SecretXV]

Type

• Bug fix (non-breaking change which fixes an issue): Fixes #
• New feature (non-breaking change which adds functionality). Resolves #
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

Checklist:

• I have run python util/check_style.py --apply to apply Open3D code style
  to my code.
• This PR changes Open3D behavior or adds new functionality.
  • Both C++ (Doxygen) and Python (Sphinx / Google style) documentation is
    updated accordingly.
  • I have added or updated C++ and / or Python unit tests OR included test
    results (e.g. screenshots or numbers) here.
• I will follow up and update the code if CI fails.
• For fork PRs, I have selected Allow edits from maintainers.

Description

This PR is the part I of integration Paddle to ml module.

More details: #7027

We don't integrate Paddle unit test to workflow currently (this will be implement at part II). So we provide a method to build from source to reproduce our works.

Environment

name	version
Python version	3.8
cuda version	11.8
ubuntu version	20.04

NOTE: we not verify other environment currently.

How to build

1. Install dependencies

util/install_deps_ubuntu.sh

2. Install paddlepaddle-gpu

python -m pip install --pre paddlepaddle-gpu -i https://www.paddlepaddle.org.cn/packages/nightly/cu118/

3. Config

mkdir build
cd build
cmake  -DBUILD_CUDA_MODULE=ON \
             -DBUILD_PADDLE_OPS=ON  \
             -DGLIBCXX_USE_CXX11_ABI=ON \
             -DBUNDLE_OPEN3D_ML=OFF \
             ..

4. Build

make -j8

5. Install

make install-pip-package

6. Verify

python -c "import open3d.ml.paddle"

The result should be showed as below.

[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.

[SecretXV]

Hey @ssheorey @benjaminum . Can you help me review this PR ？