Enable structured outputs for Google AI

[sglyon]

This quick change is something I needed locally to get structured JSON outputs from the gemini models: https://ai.google.dev/gemini-api/docs/structured-output?lang=rest

[brainlid]

Thanks for working to add structured output for Google Gemini!

I'm wondering, does adding structured output really remove the ability to set topP and topK?

I'd love to see some test coverage for the addition as well, to help ensure it doesn't have an unintended regression at some point.

And, assuming that the topP and topK are still valid, then the settings could be added to the config map in another way.