Reorganize python client library

[jasoonn]

Why are these changes needed?

Errors occur when I tried to run the example in the Python client library and import functions from the package. It seems to be related to the packing for Python Client Library.

1. Error when running example

cd path/to/kuberay/clients/python-client/python_client
pip install -e .
cd ../examples/
python3 complete-example.py 

2. Error when import in python

Reorganize the structure for the Python client.

1. Moved pyproject.toml to its parent folder which enable kuberay_cluster_api.py to be packed into Python client package.
2. Fixed import path in the python client library.

How to test

1. Unittest(Need k8s cluster already setup)

cd path/to/kuberay/clients/python-client
pip install -e .
cd python_client_test/
python3 -m unittest

2. Running examples(Need Kuberay operator already installed)

cd path/to/kuberay/clients/python-client
pip install -e .
cd examples/
python3 complete-example.py 

3. Using python to import the module anywhere

Related issue number

Checks

• I've made sure the tests are passing.
• Testing Strategy
  • Unit tests
  • Manual tests
  • This PR is not tested :(

[kevin85421]

cc @Yicheng-Lu-llll

[kevin85421]

LGTM

# Step 1: Install Python client (path: kuberay/clients/python-client)
pip install -e .

# Step 2: Run tests (path: kuberay/)
# (test_api.py, test_director.py, test_utils.py)
python -m unittest discover clients/python-client/python_client_test/

# Run examples (path: kuberay/clients/python-client/examples)
# I ran every example under this folder manually.
python3  use-utils.py