Update distributed training CLI to add "ray" framework.

[qiuosier]

The support for Ray has been added to ADS distributed training.
https://github.com/oracle-samples/oci-data-science-ai-samples/blob/main/distributed_training/ray.md

We need to update ads opctl distributed-training CLI to take "ray" as a valid framework.

With this PR, users can run the following command to download the artifacts:

ads opctl distributed-training init --framework ray

Downloading from https://raw.githubusercontent.com/oracle-samples/oci-data-science-ai-samples/master/distributed_training/artifacts/ray_v1.tar.gz to .tmp_ray_v1.tar.gz
x ray/
x ray/v1/
x ray/v1/Dockerfile
x ray/v1/README.md
x ray/v1/__init__.py
x ray/v1/cleanup.py
x ray/v1/cleanup.sh
x ray/v1/environment.yaml
x ray/v1/ray_cluster.py
x ray/v1/run.py
x ray/v1/run.sh
x ray/v1/start-head.sh
x ray/v1/start-worker.sh
Check oci_dist_training_artifacts/ray/v1/README.md for build instructions

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