Synchronous prevent default (#2792)

* add prevent default methods to the event

* sync prevent default almost working

* sync prevent default working

* Move event handling into the runtime

* update core tests

* restore desktop file dialog

* implement prevent default on web

* add a hint about the new prevent default method

* fix web prevent default

* Fix CTRL+click on links

* fix values memorize in place test

* Fix a few more tests

* Add a playwright test for sync prevent default

* Fix core doc tests

* create a deprecated VirtualDom::handle_event

* fix macos imports in desktop

* Fix onmounted event

* Fix liveview support

* switch to RefCell for metadata

* Remove println

* remove prevent default attribute

* remove web specific link behavior

* Fix liveview links

* more liveview fixes for link

* Fix merge conflicts

* Fix clippy

* use the new prevent default in the file upload example

examples/file_upload.rs

@@ -73,11 +73,14 @@ fn app() -> Element {
 
         div {
             id: "drop-zone",
-            prevent_default: "ondragover ondrop",
             background_color: if hovered() { "lightblue" } else { "lightgray" },
-            ondragover: move |_| hovered.set(true),
+            ondragover: move |evt| {
+                evt.prevent_default();
+                hovered.set(true)
+            },
             ondragleave: move |_| hovered.set(false),
             ondrop: move |evt| async move {
+                evt.prevent_default();
                 hovered.set(false);
                 if let Some(file_engine) = evt.files() {
                     read_files(file_engine).await;