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.

packages/hooks/src/use_callback.rs

@@ -11,7 +11,13 @@ pub fn use_callback<T: 'static, O: 'static>(f: impl FnMut(T) -> O + 'static) ->
 
     // Create a copyvalue with no contents
     // This copyvalue is generic over F so that it can be sized properly
-    let mut inner = use_hook(|| Callback::new(callback.take().unwrap()));
+    let mut inner = use_hook(|| {
+        Callback::new(
+            callback
+                .take()
+                .expect("Callback cannot be None on first call"),
+        )
+    });
 
     if let Some(callback) = callback.take() {
         // Every time this hook is called replace the inner callback with the new callback