Support async methods in the JavaScript kit

[Angelmmiguel]

Is your feature request related to a problem? Please describe.

Currently, the JavaScript workers don't allow you to use async methods for handlers. In some cases, this is convenient as the methods may need to wait for some resources before returning the response. Async methods are supported since Javy 1.0.0, so we should be able to implement them in wws.

This is an example of an async worker:

// Using an async function to reply!
async function handle(request) {
  // Body response
  const body = `Hello world!`;

  // Build a new response
  let response = new Response(body);

  // Add a new header
  response.headers.set("x-generated-by", "wasm-workers-server");

  return response;
}

addEventListener('fetch', event => {
  event.respondWith(handle(event.request));
});

Even though it doesn't require an async method, we can use it as an example.

Describe the solution you'd like

I would like to use async when defining methods in JavaScript workers. Some libraries and several examples that I found require this feature.

It's available in Javy 1.0.0, so it may require to upgrade the JavaScript kit and start using the new crate from the Javy team: https://crates.io/crates/javy.

Describe alternatives you've considered

No response

Additional context

No response