more fullstack cleanups: loaders serialize, ServeConfig only (#4785)

* some opinionated cleanups in dioxus-server

* add serialize to loader

* add `result` to Resource

* clippy

* fix

* writable memos, resources, `onmount`, `.pending`, and `.value()` on actions

* fix compile issues

* fix typo

examples/07-fullstack/middleware.rs

@@ -37,7 +37,7 @@ fn app() -> Element {
     rsx! {
         h1 { "Fullstack Middleware Example" }
         button { onclick: move |_| per_route.call(), "Fetch Data" }
-        pre { "{per_route.result():#?}" }
+        pre { "{per_route.value():#?}" }
     }
 }