feature: Support self-hosted s3 compatible storage

[erhwenkuo]

For many company, which hosted their own s3 compatible storage on premise (like Minio). It's very important to allow retrieve llm related model file from on-premise S3 storage.

In order to fulfill this feature, the system might need to allow setup three parameters for S3:

1. AWS_ACCESS_KEY_ID
2. AWS_SECRET_ACCESS_KEY
3. AWS_ENDPOINT_URL

The #1&#2 already cover in current KUBEAI design. I would suggest to add #3 (AWS_ENDPOINT_URL) to current design, so it will attract more enterprise to adopt KUBEAI.

[samos123]

vllm 0.6.6 now supports S3 compatible storage using RunAI model stream. That would allow setting all those parameters using environment variables: https://github.com/run-ai/runai-model-streamer/blob/master/docs/src/env-vars.md

I will test the new vLLM release and update the helm chart.