[R-304] support more providers for `is_finished()` logic

[jjmachan]

Suggest improvements to the parser for figuring out if the model finish reasons so that the default parser can be improved

you can also define your own custom parser and parse it too

_R-304

[ahgraber]

Llama models hosted on TogetherAI use {"finish_reason": "eos"}

{
  "content": "The letter 'r' appears twice in the word 'strawberry'.",
  "additional_kwargs": {
    "refusal": null
  },
  "response_metadata": {
    "token_usage": {
      "completion_tokens": 16,
      "prompt_tokens": 54,
      "total_tokens": 70,
      "completion_tokens_details": null,
      "prompt_tokens_details": null
    },
    "model_name": "meta-llama/Meta-Llama-3.1-70B-Instruct-Turbo",
    "system_fingerprint": null,
    "finish_reason": "eos",
    "logprobs": null
  },
  "type": "ai",
  "name": null,
  "id": "run-16ae060b-4bc2-4624-b07e-dce650033d6c-0",
  "example": false,
  "tool_calls": [],
  "invalid_tool_calls": [],
  "usage_metadata": {
    "input_tokens": 54,
    "output_tokens": 16,
    "total_tokens": 70,
    "input_token_details": {},
    "output_token_details": {}
  }
}

[jjmachan]

hey @ahgraber thanks for reporting this as always 🙂 I'll add it to that