In order to demonstrate the new functionality, changed the example to
download the images from the network, scale and show them by attaching
different continuations to QFuture. Because QtConcurrent::map is not
used anymore, removed the suspension functionality (supporting
suspension of download would complicate the logic).
Task-number: QTBUG-87205
Change-Id: I5a48b63195d28025ae8c5de28bc6d6178dad03db
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>
