Update copyright headers

Qt copyrights are now in The Qt Company, so we could update the source
code headers accordingly. In the same go we should also fix the links to
point to qt.io.

Change-Id: I6aafb5f38bfaf68a9f4eaca69a56006db5cd8843
Reviewed-by: Jani Heikkinen <jani.heikkinen@theqtcompany.com>
Reviewed-by: aavit <eirik.aavitsland@theqtcompany.com>