Add store parameter to request

[hugohmn]

Hello,

Would be great to add the new parameter store to requests, to be able to use evaluations and distillation features.

see :
https://community.openai.com/t/chat-completions-history-on-openai-dashboard/987804
https://platform.openai.com/docs/guides/distillation/send-fine-tuned

Maybe something that would look like this :

let request = CreateChatCompletionRequestArgs::default()
        .max_tokens(512u32)
        .model("gpt-4o-mini")
        .messages([
            ChatCompletionRequestUserMessageArgs::default()
                .content("Hi")
                .build()?
                .into(),
        ])
        .store(true)
        .build()?;

Thanks