Preinstall qt6 for Windows and Macos to reduce build time #962
Description
Currently, the builds for windows and macos rely on a cache that does not include qt6. Therefore the builds are losing time installing qt6 in those systems. This steals roughly 5 minutes to each build task.
This issue can be solved using docker images, just like we currently use for linux. In this case we would no longer need cachés and the build scripts will simplify greatly. (The example is the linux build script)
Possible images to start with https://www.it-connect.fr/dockur-executer-windows-11-tiny-11-et-macos-avec-docker/
A main advantage is to be able to launch cibuildwheel always from within ubuntu with python 3.14 and produce wheels for all systems using those docker images. This would simplify greatly everything.
Another advantage is the activation of qt6 visualization in windows ;)
EDIT: This has been proven harder than I originally thought, docker does not have cross-building compatibility. In any case the cachés should have qt6 installed. This shall be done with aqtinstall. This would install qt6 inside the /software folder and will be cached. This is valid for Windows and Macos.