Spring-ai OpenAi: Add support for structured outputs and JSON schema

• Added support for OpenAI's structured outputs feature, which allows specifying a JSON schema for the model to match
• Introduced new record to configure the desired response format
• Added support for configuring the response format via application properties or the chat options builder
• Extend teh BeanOutputConverter to help generate JSON schema from a target domain object and convert the response.
• Added comprehensive tests to cover the new response format functionality

Resolves #1196

Comment From: markpollack

closed in 91afed5ae5baf36a56b96dc2a4f31805a2f4e05e