Add capability of creating seperated stencil view in OpenGL.

[hzqst]

See #689

TODO: Do we need to check if GL_ARB_stencil_texturing available, or force a OpenGL 4.3 core profile prerequsite?

GL_ARB_stencil_texturing checking added.

[TheMostDiligent]

There are also minor formatting issues

[TheMostDiligent]

There are still some formatting issues that remain:

https://github.com/DiligentGraphics/DiligentCore/actions/runs/16670522485/job/47209765341?pr=690

[hzqst]

[ 88%] Building CXX object Graphics/GraphicsEngineVulkan/CMakeFiles/Diligent-GraphicsEngineVk-static.dir/src/ShaderResourceCacheVk.cpp.o
/Users/runner/work/DiligentCore/DiligentCore/Graphics/GraphicsEngineOpenGL/src/TextureBaseGL.cpp:507:55: error: use of undeclared identifier 'GL_DEPTH_STENCIL_TEXTURE_MODE'
                        glTexParameteri(GLViewTarget, GL_DEPTH_STENCIL_TEXTURE_MODE, GL_STENCIL_INDEX);
                                                      ^
/Users/runner/work/DiligentCore/DiligentCore/Graphics/GraphicsEngineOpenGL/src/TextureBaseGL.cpp:507:86: error: use of undeclared identifier 'GL_STENCIL_INDEX'
                        glTexParameteri(GLViewTarget, GL_DEPTH_STENCIL_TEXTURE_MODE, GL_STENCIL_INDEX);
                                                                                     ^
[ 88%] Building CXX object Graphics/GraphicsEngineOpenGL/CMakeFiles/Diligent-GraphicsEngineOpenGL-static.dir/src/TextureCube_GL.cpp.o

Do we need to define GL_DEPTH_STENCIL_TEXTURE_MODE and GL_STENCIL_INDEX by ourself if they were not defined by platform specified GL headers? If we do so, put the definition at ?

[TheMostDiligent]

Yes, the definitions are in GLStubsAndroid.h and GLStubsIOS.h.

[TheMostDiligent]

https://github.com/DiligentGraphics/DiligentCore/actions/runs/16678796778/job/47212189059?pr=690

When configuring CMake, you should set -D DILIGENT_NO_FORMAT_VALIDATION=OFF. This will add format validation targets to the project.