Function app_load_file_preview 

pub async fn app_load_file_preview(
    configuration: &Configuration,
    workspace: &str,
    path: &str,
    file_key: &str,
    read_bytes_from: i32,
    read_bytes_length: i32,
    file_size_in_bytes: Option<i32>,
    file_mime_type: Option<&str>,
    csv_separator: Option<&str>,
    csv_has_header: Option<bool>,
    storage: Option<&str>,
) -> Result<WindmillFilePreview, Error<AppLoadFilePreviewError>>