allow user to override ChatConfig when creating LanguageModel for LMStudio (openAiCompatible) Provider

[Sewdn]

See discussion in #5197 (comment)

This PR now allows to optionally override languageModel configuration properties defaultObjectGenerationMode and supportStructuredOutputs.

When setting supportStructuredOutputs to true, this will now make the openAiCompatible provider add the schema to the request when generating objects (and when a schema was provided).

This is how this change can be used:

const lmstudio = createOpenAICompatible({
    name: 'lmstudio',
    baseURL: 'http://localhost:1234/v1',
});
model = lmstudio('mistral-nemo-instruct-2407', undefined, {
    supportsStructuredOutputs: true,
});

It is not ideal to have to add an undefined settings, since the extra config that was added to the function's signature is added as last optional parameter, to allow for backwards compatibility.

Better would be to add overloaded function signatures to allow for all possible construction methods:

model = lmstudio('mistral-nemo-instruct-2407');
model2 = lmstudio({
  modelId: 'mistral-nemo-instruct-2407', 
  config: {
    supportsStructuredOutputs: true,
  }
});

[Sewdn]

@lgrammel Can you review or assign reviewer? Thanks!