The feature is only available in QDS mode.
This adds a combobox to the run configuration which allows
the easy selection of a Qt 5 or Qt 6 kit.
Task-number: QDS-4733
Change-Id: I53fae9fe4bc415e5b1e8d385ef85ed81b8010b3a
Reviewed-by: Henning Gründl <henning.gruendl@qt.io>