Support adding code to generated classes - e.g.: `model_config = ConfigDict(protected_namespaces=())`

[msabramo]

Problem

https://github.com/BerriAI/litellm uses prisma-client-py and it happens to define some fields that start with model_ and this causes Pydantic to complain with a bunch of warnings like this:

UserWarning: Field "model_max_budget" in LiteLLM_BudgetTable 
has conflict with protected namespace "model_".

Suggested solution

It would be nice to be able to get rid of these warnings. To do this the generated code would have to have:

model_config['protected_namespaces'] = ()

or something similar.

Ideally, this would be configurable so that most projects don't have to turn off this checking.

One possible way to solve this is if prisma-client-py had a config option like pyantic_disable_protected_namespaces that would cause it to add the necessary code. PR: #983

Alternatives

Another option is a more general feature that allows adding any arbitrary Python code to the generated class. This would be more powerful but probably much harder to implement.

Additional context