[feature request] Ability to describe an async component

[bigopon]

🔦 Context

At the moment, loading components asynchronously can be done via <au-compose/>, though it's not always desirable since this way comes with some boilerplate:

<au-compose component.bind="loadMyComponent()">

This is also hard for bundler to statically analyse. Ideally we should have a way to declare an async component in a simpler/direct way:

export const MyElement = CustomElement.async(() => import('path/to-));

Another declarative-ish form of this is the html equivalent:

<template as-custom-element="my-component" async="path/to/...">

cc @Sayan751 @fkleuver

[Sayan751]

@bigopon Sounds like a great idea. I think it is would be a great addition for a future minor version.