add .with support to handler output

[seefeldb]

  const clickHandler = handler(...);
  ...
  <button onclick={clickHandler({ item }))>

is a bit confusing as it looks like it's called when an event happens, but really we're creating an event handler ahead of timing and binding data to it.

This PR adds a .with method to handlers, so that we can write

  <button onclick=`{clickHandler.with({ item })}`>

which hopefully is a bit clearer.

This PR also overrides .bind to do the same, and then calls the handler with the state parameter bound to this. This requires passing an anonymous function instead of an arrow function:

    const incHandler = handler<
      { amount: number },
      { counter: { value: number } }
    >(function ({ amount }) {
      this.counter.value += amount;
    });

or just

    const incHandler = handler(function (event) {
      this.counter.value += event.amount;
    });