Adjusting for Windows Scaling broken with Qt6

[psieg]

I recently switched the master branch to build using Qt6 and it seems Qt6 handles something about windows scaling differently from how Qt5 did. Now capturing on displays with scaling is off, i.e. it's not capturing where the grab widgets are.

https://doc.qt.io/qt-6/highdpi.html

I also noticed that when configuring the layout at one scale and then switching scale, the grab widgets move, which didn't happen with Qt5.

[psieg]

@zomfg you are on mac, right? I merged Qt6 on master, could you please test whether mac needs the same coordinate adjustments here: https://github.com/psieg/Lightpack/blob/97955fec7256157d20bb2577467d20cf9fb10e01/Software/grab/GrabberBase.cpp#L177