Find missing Qt version when creating MCU kit

When creating a kit for Qt for MCUs for the desktop target, the Qt version is added to it (a link to an existing Qt kit).

However, that is not the case when the target is either NXP or STM32: No Qt kit is linked.  When the user runs CMake, it will fail the moment the dependency to Qt is checked.   To troubleshoot this manually, the user has to go to the kit manager in the options dialog and select a valid version of Qt in the corresponding MCU kit.

Investigate why the link to Qt is missing in this case and add it.