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/08-apis/ssr.rs

@@ -0,0 +1,42 @@
+//! Example: SSR
+//!
+//! This example shows how we can render the Dioxus Virtualdom using SSR.
+//! Dioxus' SSR is quite comprehensive and can generate a number of utility markers for things like hydration.
+//!
+//! You can also render without any markers to get a clean HTML output.
+
+use dioxus::prelude::*;
+
+fn main() {
+    // We can render VirtualDoms
+    let vdom = VirtualDom::prebuilt(app);
+    println!("{}", dioxus_ssr::render(&vdom));
+
+    // Or we can render rsx! calls themselves
+    println!(
+        "{}",
+        dioxus_ssr::render_element(rsx! {
+            div {
+                h1 { "Hello, world!" }
+            }
+        })
+    );
+
+    // We can configure the SSR rendering to add ids for rehydration
+    println!("{}", dioxus_ssr::pre_render(&vdom));
+
+    // We can render to a buf directly too
+    let mut file = String::new();
+    let mut renderer = dioxus_ssr::Renderer::default();
+    renderer.render_to(&mut file, &vdom).unwrap();
+    println!("{file}");
+}
+
+fn app() -> Element {
+    rsx!(
+        div {
+            h1 { "Title" }
+            p { "Body" }
+        }
+    )
+}