Automated setup for debugging the generated QUL code in Qt Creator

Enable debugging and stepping through the generated C++ code in Qt Creator. This is necessary at least until we have QML source maps and have some ability to enable debugging QML directly, although even then it might be useful to still debug the generated C++ code in some cases.

Currently, it is possible to debug C++ using the Bare Metal plugin, but not with the MCU support plugin. It results in an odd situation where users need to use one kit for building and flashing, and another kit for debugging.
Should we reuse the Bare Metal plugin code for debugging support? Any other way?