feat: make hooks free-functions

examples/coroutine.rs

@@ -32,13 +32,13 @@ static App: FC<()> = |cx| {
     let p2 = use_state(cx, || 0);
 
     let (mut p1_async, mut p2_async) = (p1.for_async(), p2.for_async());
-    let (p1_handle, _) = cx.use_task(|| async move {
+    let (p1_handle, _) = use_task(cx, || async move {
         loop {
             *p1_async.get_mut() += 1;
             async_std::task::sleep(std::time::Duration::from_millis(75)).await;
         }
     });
-    let (p2_handle, _) = cx.use_task(|| async move {
+    let (p2_handle, _) = use_task(cx, || async move {
         loop {
             *p2_async.get_mut() += 1;
             async_std::task::sleep(std::time::Duration::from_millis(100)).await;