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/streaming_file_upload.rs

@@ -80,7 +80,7 @@ fn app() -> Element {
                     },
                     "Drop files here"
                 }
-                pre { "{upload_as_file_upload.result():?}" }
+                pre { "{upload_as_file_upload.value():?}" }
             }
 
             div {
@@ -99,9 +99,9 @@ fn app() -> Element {
             div {
                 h3 { "Download a file from the server" }
                 button { onclick: move |_| download_file.call(), "Download file" }
-                if let Some(Ok(content)) = &download_file.result() {
+                if let Some(Ok(content)) = &download_file.value() {
                     pre { "{content}" }
-                } else if let Some(Err(e)) = &download_file.result() {
+                } else if let Some(Err(e)) = &download_file.value() {
                     pre { "Error downloading file: {e}" }
                 }
             }