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/login_form.rs

@@ -34,7 +34,7 @@ fn app() -> Element {
             },
             "Get Sensitive Data",
         }
-        pre { "Response from locked API: {fetch_sensitive.result():?}"}
+        pre { "Response from locked API: {fetch_sensitive.value():?}"}
         form {
             onsubmit: move |evt: FormEvent| async move {
                 // Prevent the browser from navigating away.