Components lack a async hook, which allows to load data async.

## Use case When I create a component, I would like to load data from an API using the `pyscript.fetch` function, which is async. ## What I tried This can not be done during `populate()` because the function is synchron. triggering an event, which could be used to trigger the data loading does also not work, because at the time of `populate()` the element is not part of the DOM. I found the undocumented on_ready callback on the component, but it is also synchron, so fetching data is also no option here. ## My solution so far I use the `on_reaady` method to trigger an `effect` event, which triggers an async `on_effect` method, which can load data async ✨ ``` class CustomPage(Page): def __init__(self, *args, **kwargs): super().__init__(*args, on_effect=self._on_effect, **kwargs) def on_ready(self): self.trigger_event("effect") async def _on_effect(self, _): # pass the event to the on_effect method, without the obsolete event argument await self.on_effect() async def on_effect(self): """Called after the page is ready.""" pass @app.page() class DefaultPage(CustomPage): def initial(self): return {"items": [], "loading": True} async def on_effect(self): await fetch(....) ``` > PS would be great to add `on_ready` to the docs.