provide tools for multiple function calling

[rgbkrk]

Partially closes #118. I went after just making it easy to export the listing of tools from a FunctionRegistry. Follow on in ChatLab's Chat can come next.

An example chat loop using tools:

async def chatloop(initial_messages):
    buffer = initial_messages.copy()

    resp = client.chat.completions.create(
        model="gpt-3.5-turbo-1106",
        messages=initial_messages,

        # Pass in the tools from the function registry. The model will choose
        # whether it uses 0, 1, 2, or N many tools.
        tools=fr.tools,
        tool_choice="auto"
    )

    message = resp.choices[0].message
    buffer.append(message)

    yield message

    # call each of the tools
    if message.tool_calls is not None:
        for tool in message.tool_calls:
            result = await fr.call(tool.function.name, tool.function.arguments)

            # An assistant message with 'tool_calls' must be followed by tool messages responding to each 'tool_call_id'.
            tool_call_response = {
                "tool_call_id": tool.id,
                "role": "tool",
                "name": tool.function.name,
                "content": str(result)
            }
            yield tool_call_response
            buffer.append(tool_call_response)
        
        # Once all tools have been called, call the model again
        async for m in chatloop(buffer):
            yield m

In use:

[rgbkrk]

Ran across this openai/openai-python#1078