Wayland Nvidia situation for initial Plasma 6 release

[David Redondo]

Hi, 

when using Wayland on Nvidia there is a significant problem that QtQuick 
windows freeze when resized, this can also manifest in plasma popups sometimes
not showing up. 
ref. https://bugreports.qt.io/browse/QTBUG-95817
This can be worked around with using the basic render loop instead of the 
threaded one.
With https://codereview.qt-project.org/c/qt/qtwayland/+/536040 Qt will now
disable threaded rendering on NVidia. However this patch missed 6.6.2 and will
be released with 6.6.3. Given that 6.6.2 is the latest patch version released
for Plasma 6.0 and the Wayland session is the new default we need to do 
something. Options that I can think of are

- tell distros to include this patch in their QtWayland builds
- disable threaded rendering in plasma-integration on Nvidia and running 
anything less than Qt 6.6.3

Thoughts?

David