Return more information

[AlmogBaku]

Instead of returning only the “functions called” and “unstreamed response message”, return a comprehensive bag of information as a Response class that contains:

1. Functions called
2. Unstreamed reaponse messages
3. Tool response messages
4. Output tokens
5. (optional) input tokens
6. Latency stats

By making this a class we can also ensure the API won't break again