qt: probe and use D3D11 if functional on Windows 7

Drivers implementing desktop OpenGL on Windows have been known for their notoriously bad functionality.

Windows 7 supports D3D12, D3D11 and Vulkan. If possible, we should use these over OpenGL.

Previously we were forcing OpenGL on Windows 7 as a safe option. The investigation showed that the features used from D3D11 by Qt may not be supplemented in Windows 7 graphics drivers. However, this does not mean that this is the case at all times.