Llama multiple function calls + raw_mode

[andthattoo]

• Added support for multiple function calls for Llama3.1 models Multiple function calls aren't supported #75
• Added raw_mode for function call, which results in returning raw function calls without executing the tools and returning results. You do this by simply calling raw_mode() at the end of the function call

    let result = ollama
        .send_function_call(
            FunctionCallRequest::new(MODEL.to_string(), vec![search], vec![user_message])
                .raw_mode(),
            parser,
        )
        .await
        .unwrap();

[andthattoo]

@pepperoni21 this is some useful functionality for function calling with llama models!

[pepperoni21]

Thanks for the contribution!