It's responsible for showing progress of the running task tree.
It's able to cancel the running task tree automatically after
pressing a small 'x' indicator on progress panel.
In this case TaskTree::stop() method is being called.
Change-Id: Ia1b3d88de74571e3e56f431b1a31755492ad4aa2
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
