Adding extraBody to OllamaChatOptions

Expected Behavior

OpenAIChatOptions supports extraBody that accepts a Map<String, Object> this is added to the request. This feature is usefull when using an OpenAI compatible provider like Perplexity that can use multiple models and extra options.
I would like to suggest you add the same to OllamaChatOptions since it is often used to self host OSS models the provide a variety of options.

Context

I have used a ClientHttpInterceptor for RestClient and ExchangeFilterFunction with a BodyInserter to add extra options to the request for calls to Ollama. We are developing an application that should work with multiple models and provides for configuration according to what the model allows.
It is obvious that the user is responsible for provide valid properties.

It would be useful when and error 400 occur that the body is dumped. Since the LLM may provide feedback on invalid properties.

Start by locating OllamaChatOptions and the existing OpenAIChatOptions support for extraBody, then trace how Ollama request bodies and HTTP 400 errors are handled. Done means callers can supply extra request properties through OllamaChatOptions and receive the response body for invalid-property errors, with focused tests covering both behaviors.