QDB on Qt 6 and CMAKE

Move QDB (Qt Debug Bridge) to using Qt 6 and possibly CMAKE. Qt 5 QDB is based on QMAKE and that needs to be changed to CMAKE.

Note that there are two parts of QBD: The host side module integrated in both Qt Creator and Qt Design Studio and target side daemon / listener.

Note that QDB is supported on all hosts (Qt 6.1 hosts here: QTBUG-86432, QDB + macOS done here: QTBUG-76086) where Qt DC is only supported on in and Linux hosts (but not macOS, yet).