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/03-assets-styling/meta_elements.rs

@@ -0,0 +1,20 @@
+//! This example shows how to add metadata to the page with the Meta component
+
+use dioxus::prelude::*;
+
+fn main() {
+    dioxus::launch(app);
+}
+
+fn app() -> Element {
+    rsx! {
+        // You can use the Meta component to render a meta tag into the head of the page
+        // Meta tags are useful to provide information about the page to search engines and social media sites
+        // This example sets up meta tags for the open graph protocol for social media previews
+        Meta { property: "og:title", content: "My Site" }
+        Meta { property: "og:type", content: "website" }
+        Meta { property: "og:url", content: "https://www.example.com" }
+        Meta { property: "og:image", content: "https://example.com/image.jpg" }
+        Meta { name: "description", content: "My Site is a site" }
+    }
+}