Docker run support for HF_TOKEN authentication using env var pass in

[tstescoTT]

To keep convention with vLLM Docker containers described in https://github.com/vllm-project/vllm/blob/main/docs/source/serving/deploying_with_docker.rst, e.g.:

docker run --runtime nvidia --gpus all \
    -v ~/.cache/huggingface:/root/.cache/huggingface \
    --env "HUGGING_FACE_HUB_TOKEN=<secret>" \
    -p 8000:8000 \
    --ipc=host \
    vllm/vllm-openai:latest \
    --model mistralai/Mistral-7B-v0.1

HUGGING_FACE_HUB_TOKEN is being deprecated in favor of HF_TOKEN as defined in https://huggingface.co/docs/huggingface_hub/en/package_reference/environment_variables#deprecated-environment-variables, so it's recommended to use HF_TOKEN here.

This could be used to allow users to download models without having to enter credentials manually where possible.

[tstescoTT]

Addressed in #67