Windows Open GL blacklist: Introduce keyword "disable_rotation".

Add a flag to disable rotation to the Renderers enumeration of
QWindowsOpenGLTester triggered by the keyword "disable_rotation".
Specifying this keyword forces the application to landscape mode
for Desktop GL. It is intended for drivers that have issues with rotation.

Task-number: QTBUG-49541
Change-Id: I0f0bb7415c59e98648be09b34a59dd201d52b211
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>