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/04-managing-state/reducer.rs

@@ -0,0 +1,56 @@
+//! Example: Reducer Pattern
+//! -----------------
+//!
+//! This example shows how to encapsulate state in dioxus components with the reducer pattern.
+//! This pattern is very useful when a single component can handle many types of input that can
+//! be represented by an enum.
+
+use dioxus::prelude::*;
+
+const STYLE: Asset = asset!("/examples/assets/radio.css");
+
+fn main() {
+    dioxus::launch(app);
+}
+
+fn app() -> Element {
+    let mut state = use_signal(|| PlayerState { is_playing: false });
+
+    rsx!(
+        Stylesheet { href: STYLE }
+        h1 {"Select an option"}
+
+        // Add some cute animations if the radio is playing!
+        div { class: if state.read().is_playing { "bounce" },
+            "The radio is... " {state.read().is_playing()} "!"
+        }
+
+        button { id: "play", onclick: move |_| state.write().reduce(PlayerAction::Pause), "Pause" }
+        button { id: "pause", onclick: move |_| state.write().reduce(PlayerAction::Play), "Play" }
+    )
+}
+
+enum PlayerAction {
+    Pause,
+    Play,
+}
+
+#[derive(Clone)]
+struct PlayerState {
+    is_playing: bool,
+}
+
+impl PlayerState {
+    fn reduce(&mut self, action: PlayerAction) {
+        match action {
+            PlayerAction::Pause => self.is_playing = false,
+            PlayerAction::Play => self.is_playing = true,
+        }
+    }
+    fn is_playing(&self) -> &'static str {
+        match self.is_playing {
+            true => "currently playing!",
+            false => "not currently playing",
+        }
+    }
+}