[IMP] blockdom: t-on supports synthetic and native event handler

Synthetic handler is a sort of event delegation that allows placing
only one listener on the document to improve performance. It is an opt-in option.

Native listener places the listener on the node itself.

tests/components/event_handling.test.ts

@@ -33,7 +33,7 @@ describe("event handling", () => {
     expect(fixture.innerHTML).toBe("<span><div>simple vnode</div>2</span>");
   });
 
-  test.skip("support for callable expression in event handler", async () => {
+  test("support for callable expression in event handler", async () => {
     class Counter extends Component {
       static template = xml`
       <div><t t-esc="state.value"/><input type="text" t-on-input="obj.onInput"/></div>`;