Add hotkeys and async action web component examples.

[richard-to]

Now that the child components issue has been fixed (#449), the hotkeys web component that I was working on a few weeks ago is working now.

Also adding the async action web component example.

[wwwillchen]

These are some pretty interesting web components. I'm wondering if should: a) support some of these things natively in mesop or b) make it easier to reuse web components across apps (e.g. mesop add foo-component) - WDYT?

[richard-to]

Those are great questions. I definitely think the hot key thing would be nice to support natively in mesop. I think we already have a Github issue for it. And I think to do "async actions" in a more full featured way, we'd probably need native support. I think the FastAPI middleware integration could potentially help with this since long running API calls could potentially be sent to a FastAPI endpoint. Something like celery integration would be nice (or whatever is better than celery nowadays). Does GCP have anyway to implement LRO APIs? Maybe revisit Websockets.

But I do like starting off with a web components since it's a cheap way to test out the behavior and usage in the short term. I definitely think the mesop add foo-component can be useful as well in general to improve sharing of components (granted we don't have much of an ecosystem yet).

So I think both ideas are useful.