flow.start() should give server-side full control over the page

[vlukashov]

The code below should start the server-side Flow app and let it have the full control of the browser page, including click handling and navigation. The app started that way should work the same as a v14 app started with the BoostrapHandler except that if there are any listeners registered with BootstrapHandler, they are not executed.

import { Flow } from '@vaadin/flow';

const flow = new Flow({
    imports: () => import('../target/frontend/generated-flow-imports')
});

document.querySelector('button').addEventListener('click', () => {
    flow.start();
});