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/10-integrations/pwa/src/main.rs

@@ -0,0 +1,15 @@
+use dioxus::prelude::*;
+
+fn main() {
+    dioxus::launch(app);
+}
+
+fn app() -> Element {
+    rsx! (
+        div { style: "text-align: center;",
+            h1 { "🌗 Dioxus 🚀" }
+            h3 { "Frontend that scales." }
+            p { "Build web, desktop, and mobile apps with Dioxus" }
+        }
+    )
+}