switch to a Document trait and introduce Script/Head/Style/Meta components (#2635)

* switch to a Document trait and introduce Script/Head/Style/Meta components

* Fix desktop title

* Insert special elements into the head during the inital SSR render

* Make all head component attributes optional

* hydrate head elements

* improve the server streaming head warning

* Document fullstack head hydration approach

* deduplicate head elements by href

* move Link into head::Link

* document head components

* add meta and title examples

* Fix a few doc examples

* fix formatting

* Add title to playwright tests

* serde is optional on web, but it is enabled by hydrate

* remove leftover console log

packages/playwright-tests/nested-suspense/src/main.rs

@@ -17,6 +17,10 @@ fn main() {
 
 fn app() -> Element {
     rsx! {
+        SuspenseBoundary {
+            fallback: move |_| rsx! {},
+            LoadTitle {}
+        }
         MessageWithLoader { id: 0 }
     }
 }
@@ -33,6 +37,17 @@ fn MessageWithLoader(id: usize) -> Element {
     }
 }
 
+#[component]
+fn LoadTitle() -> Element {
+    let title = use_server_future(move || server_content(0))?()
+        .unwrap()
+        .unwrap();
+
+    rsx! {
+        Title { "{title.title}" }
+    }
+}
+
 #[component]
 fn Message(id: usize) -> Element {
     let message = use_server_future(move || server_content(id))?()