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/hackernews/assets/hackernews.css

@@ -0,0 +1,17 @@
+@keyframes spin {
+    0% {
+        transform: rotate(0deg);
+    }
+
+    100% {
+        transform: rotate(360deg);
+    }
+}
+.spinner {
+    width: 10px;
+    height: 10px;
+    border: 4px solid #f3f3f3;
+    border-top: 4px solid #3498db;
+    border-radius: 50%;
+    animation: spin 2s linear infinite;
+}