[Development] Desktop components: project directory structure

[Laszlo Papp]

> I want to work towards having one branch by merging over the differences and using Qt version ifdefs. I think this approach has worked well for Qt Creator on Qt 5, where we have one canonical Creator master branch and not a Qt 5 branch which lags behind.

Fwiw, we have done the same for QtSerialPort (and I would like
personally like to do the same for QtAudio3D when I have time for
that).

Best Regards,
Laszlo Papp