Have the cross-compilation environments in use for the QSR developers

In order to detect possible typos for the conditional compilation parts of the code, the developers could have the needed cross-compilation environments in use in the Qt Creator.

That would help to spot the issues sooner, see for example:

https://codereview.qt-project.org/c/tqtc-boot2qt/qtsaferenderer/+/328082

And the cross-compilation would be performed before pushing the commits for the code review.