feat: add tool calling for chatgpt-based math agent

[dongyuanjushi]

1. add tool calling for chatgpt-based math agent
2. refactor and wrap LLM request and LLM response, which can be found in utils.message.py.

Message object to wrap LLM request

class Message:
    def __init__(self,
            prompt, 
            context = None, 
            tools = None
        ) -> None:
        self.prompt = prompt
        self.context = context
        self.tools = tools

Response object to wrap LLM response

class Response:
    def __init__(
            self, 
            response_message,
            tool_calls = None
        ) -> None:
        self.response_message = response_message
        self.tool_calls = tool_calls