qt_add_add_qml_module runs into command line length limits on Windows

When using qt_add_qml_module() on Windows it will run into command line length issues when there's a large number of QML files added to a module, producing the very unhelpful error Cannot open options file specified with @.

This was encountered on KDE's Kirigami project CI, see for example https://invent.kde.org/frameworks/kirigami/-/jobs/1184162#L542 . I did try to figure out what the amount of files was that would trigger this, and in the case of Kirigami it ended up breaking at 85 QML files. However, since the limit on Windows is a character amount limit, this might be different for different projects.