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/file-explorer/README.md

@@ -0,0 +1,13 @@
+# File-explorer with Rust and Dioxus
+
+This example shows how a Dioxus App can directly leverage system calls and libraries to bridge native functionality with the WebView renderer.
+
+![example](./assets/image.png)
+
+
+## To run this example:
+
+```
+dx serve
+```
+