Function https_request_once 

fn https_request_once(
    method: &str,
    host: &str,
    path: &str,
    extra_headers: &[(&str, &str)],
    content_type: &str,
    body: Option<&[u8]>,
) -> Result<(HttpsGetResult, bool), &'static str>

https_request の 1 回ぶん。戻り値の bool は応答が最後まで届いたか。