Use of async_std::task::sleep instead of tokio::time::sleep in examples (#2912)

* Use of async_std::task::sleep instead of tokio::time::sleep

* Make the clock example run on wasm

* Add control_focus and eval examples to Cargo.toml

* Use web-time on desktop; It just falls back to std on non-wasm platforms

---------

Co-authored-by: Evan Almloff <evanalmloff@gmail.com>

examples/streams.rs

@@ -1,11 +1,11 @@
 //! Handle async streams using use_future and awaiting the next value.
 
+use async_std::task::sleep;
 use dioxus::prelude::*;
 use futures_util::{future, stream, Stream, StreamExt};
-use std::time::Duration;
 
 fn main() {
-    launch_desktop(app);
+    launch(app);
 }
 
 fn app() -> Element {
@@ -30,7 +30,7 @@ fn app() -> Element {
 fn some_stream() -> std::pin::Pin<Box<dyn Stream<Item = i32>>> {
     Box::pin(
         stream::once(future::ready(0)).chain(stream::iter(1..).then(|second| async move {
-            tokio::time::sleep(Duration::from_secs(1)).await;
+            sleep(std::time::Duration::from_secs(1)).await;
             second
         })),
     )