feat: allow 'static futures to be spawned from handlers

examples/button.rs

@@ -6,6 +6,13 @@ fn main() {
 
 fn app(cx: Scope) -> Element {
     cx.render(rsx! {
-        button { "hello, desktop!" }
+        button {
+            onclick: |e| async move {
+                println!("hello, desktop!");
+                tokio::time::sleep(std::time::Duration::from_secs(1)).await;
+                println!("goodbye, desktop!");
+            },
+            "hello, desktop!"
+        }
     })
 }