[WIP] Pixtral Text Config

[kylesayrs]

Purpose

• This is a potential solution to the issue of conflicting Pixtral and Mistral configs, as detailed here
• The downside to this approach is that (afaict) transformers makes an assumption that all configs have a one to one mapping with models. In this case, the PixtralTextConfig would map to the MistralModel, which is already associated with the MistralConfig. Additional logic and testing would be require to handle this case.

[Rocketknight1]

cc @ArthurZucker - I think this is something that's usually handled with modular instead of directly importing the config, no?

[ArthurZucker]

Was this not fixed by (#36077)?

[kylesayrs]

@ArthurZucker This was fixed by #36077, however that solution is technically a hack as it saves more attributes than are necessary and expands the use of the is_composition beyond its original intended use.

I believe that this is a good solution for now, this PR can be reopened/forked if a better solution is desired.