Using Android's UI coroutine dispatcher

With this done, we can now use the dispatcher in the same way we use any other, for example:

launch(dispatcher) {
  val headlines = fetchRssHeadlines()
  val newsCount = findViewById<TextView>(R.id.newsCount)
  launch(UI) {
    newsCount.text = "Found ${headlines.size} News"    
  }
}

Executing the code at this point will work. The quantity of news will be correctly displayed on the application.