[INFO] Document or remove `logits` from the `ModelResponse` class

@NathanHB I was exploring the ModelResponse class post refacto, and I noticed we have both logits (undocumented) and logprobs (documented) in the class. Logits is used for some classes (transforemrs) and logprob for others - I believe we should have a single class for both as they are usually used interchangeably and would allow us to have a single system. If we actually want to manage them differently, we can but it needs more documentation.