Add D3D_FEATURE_LEVEL_12_2

[2A5F]

No description provided.

[TheMostDiligent]

Hello!

This change currently fails to build with the older Windows SDK version:

C:\projects\DiligentCore\Graphics\GraphicsEngineD3DBase\include\EngineFactoryD3DBase.hpp(298,29): error C2065: 'D3D_FEATURE_LEVEL_12_2': undeclared identifier (compiling source file C:\projects\DiligentCore\Graphics\GraphicsEngineD3D12\src\EngineFactoryD3D12.cpp) [C:\projects\DiligentCore\build\Graphics\GraphicsEngineD3D12\Diligent-GraphicsEngineD3D12-static.vcxproj]

It is necessary to find out in which SDK version this enum value was first defined and add a fallback value for older SDK versions.

[2A5F]

Should use directx heades instead of windows sdk to avoid this situation

[TheMostDiligent]

Should use directx heades instead of windows sdk to avoid this situation

This will require quite a bit of work, which is not justified by this specific change.
For this PR to work, adding a fallback value is much simpler.

[TheMostDiligent]

It looks like required changes are missing here, here, and here