Support for OpenAI /v1/responses

Please do a quick search on GitHub issues first, the feature you are about to request might have already been requested.

Currencty SpringAI does not support OpenAI Response API out of the box. This missing feature prevents me from using some more advanced OpenAI models such as o3-pro which does not have chat completion endpoint

https://platform.openai.com/docs/api-reference/responses/create
