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/01-app-demos/hotdog/README.md

@@ -0,0 +1,16 @@
+# Hot diggity dog!
+
+A Dioxus demo app for the new tutorial!
+
+![Demo](assets/screenshot.png)
+
+## To run
+
+Make sure you cd to this directory (dioxus/hotdog) and then `serve` any platform:
+
+```rust
+dx serve --platform web
+dx serve --platform desktop
+dx serve --platform ios
+dx serve --platform android
+```