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/control_focus.rs

@@ -3,13 +3,15 @@
 //! This example shows how to manage focus in a Dioxus application. We implement a "roulette" that focuses on each input
 //! in the grid every few milliseconds until the user interacts with the inputs.
 
-use dioxus::prelude::*;
 use std::rc::Rc;
 
+use async_std::task::sleep;
+use dioxus::prelude::*;
+
 const STYLE: &str = asset!("./examples/assets/roulette.css");
 
 fn main() {
-    launch_desktop(app);
+    launch(app);
 }
 
 fn app() -> Element {
@@ -21,7 +23,7 @@ fn app() -> Element {
         let mut focused = 0;
 
         loop {
-            tokio::time::sleep(std::time::Duration::from_millis(50)).await;
+            sleep(std::time::Duration::from_millis(50)).await;
 
             if !running() {
                 continue;