codify "platform" into resolution logic, server-fn/fullstack overhaul (#4596)

overhaul dioxus fullstack using a new implementation of server_fn

This PR is a complete rewrite of dioxus fullstack designed to improve compatibility with axum and to fix a number of compilation errors based on feature flag unification plumbing through macros.

examples/05-using-async/future.rs

@@ -0,0 +1,49 @@
+//! A simple example that shows how to use the use_future hook to run a background task.
+//!
+//! use_future won't return a value, analogous to use_effect.
+//! If you want to return a value from a future, use use_resource instead.
+
+use async_std::task::sleep;
+use dioxus::prelude::*;
+
+fn main() {
+    dioxus::launch(app);
+}
+
+fn app() -> Element {
+    let mut count = use_signal(|| 0);
+
+    // use_future is a non-reactive hook that simply runs a future in the background.
+    // You can use the UseFuture handle to pause, resume, restart, or cancel the future.
+    use_future(move || async move {
+        loop {
+            sleep(std::time::Duration::from_millis(200)).await;
+            count += 1;
+        }
+    });
+
+    // use_effect is a reactive hook that runs a future when signals captured by its reactive context
+    // are modified. This is similar to use_effect in React and is useful for running side effects
+    // that depend on the state of your component.
+    //
+    // Generally, we recommend performing async work in event as a reaction to a user event.
+    use_effect(move || {
+        spawn(async move {
+            sleep(std::time::Duration::from_secs(5)).await;
+            count.set(100);
+        });
+    });
+
+    // You can run futures directly from event handlers as well. Note that if the event handler is
+    // fired multiple times, the future will be spawned multiple times.
+    rsx! {
+        h1 { "Current count: {count}" }
+        button {
+            onclick: move |_| async move {
+                sleep(std::time::Duration::from_millis(200)).await;
+                count.set(0);
+            },
+            "Slowly reset the count"
+        }
+    }
+}