[Inference] Support for Messages API OpenAI API specs

[radames]

Considering that TGI now supports the Messages API compatible with OpenAI API specs, it would be great to have native support in the Inference package.

curl localhost:3000/v1/chat/completions \
    -X POST \
    -d '{
  "model": "tgi",
  "messages": [
    {
      "role": "system",
      "content": "You are a helpful assistant."
    },
    {
      "role": "user",
      "content": "What is deep learning?"
    }
  ],
  "stream": true,
  "max_tokens": 20
}' \
    -H 'Content-Type: application/json'

https://huggingface.co/docs/text-generation-inference/messages_api

I tried this , but model is not send and raises a backend error

const mistral = new HfInferenceEndpoint(
  "https://api-inference.huggingface.co/models/mistralai/Mixtral-8x7B-Instruct-v0.1/v1/chat/completions",
  HF_TOKEN,
);
const stream = mistral.streamingRequest({
  model: "tgi",
  messages: [{ role: "user", content: "What's the meaning ..." }],
  parameters: {
    messages: messages,
    temperature: 0.8,
    max_new_tokens: 1000,
    repetition_penalty: 1.2,
    seed: Math.floor(Math.random() * Number.MAX_SAFE_INTEGER),
  },
});