QDS-11148 - Qt6.6 integration
Main change here is moving the "screen" element out from the "qtspinner" hierarchy, which avoids hiding it when qtspinner is hidden. Also rename it to "qtcontainer".
Other fixes:
- there is no longer a qtLoader object. We can access the instance after startup instead.
- remove old preRun workaround
- the canvas is now used only for detecting WebGL support
- call setContainerSize from onLoad
- make DesignViewer::printError() actually print the error
Closes QDS-11148
Edited by Burak Hançerli