Function make_get_handler 

fn make_get_handler<F, Fut>(
    f: F,
) -> Box<dyn Fn(Extension<Arc<Gateway>>) -> Pin<Box<dyn Future<Output = Result<Json<Value>, GatewayError>> + Send>> + Send + Sync>
where
    F: Fn(Extension<Arc<Gateway>>) -> Fut + Clone + Send + Sync + 'static,
    Fut: Future<Output = Result<Json<Value>, GatewayError>> + Send + 'static,

Creates a GET handler for the Iroh endpoint by wrapping it in a closure.