Canceling navigations

Navigations can be cancelled from the onNavigate callback.

function Route() {
	let [Form, busy, loading, navigations] = useForm();

	function handleNavigate(event) {
		event.preventDefault();
	}

	return (
		<>
			<Form method="post" onNavigate={handleNavigate}>
				...
			</Form>
		</>
	);
}