Simplify custom DOM event dispatch

[allevo]

Improve child->parent communication.
For the time being, child components can send events to parents in 2 ways:

• domain event (alway using a external domain class -> heavy)
• dom event (cannot be customizable -> bad)
  Meanwhile, the first is well-typed and structured, but the second isn't.
  We would like Seqflow helps the developer to build CustomEvent so the parent can listen it.

We can write something like

const MyNewDomEvent = createDomEventClass<{ foo: string }>('my-dom-event')

async function ChildComponent({}, { component }: Contexts) {
  // something happen
  component.dispatchEvent(new MyNewDomEvent({ foo: 'a string' }))
}
async function ParentComponent({}, { component }: Contexts) {
  // render ChildComponent

  const events = component.waitEvents(component.domEvent(MyNewDomEvent))
  for await (const ev of events) {
    console.log(ev) // ev instanceof MyNewDomEvent
  }
}

With this issue the assignee should:

• create and export a function createDomEventClass to help the developer create custom dom event
• improve the domEvent method to allow custom dom event
  The createDomainEventClass function can help.