Critical fix: For OpenGL, RenderDoc requires HGLRC (OpenGL context) as
the device pointer, not HDC. Previously OpenGL test incorrectly passed
HDC which caused capture to silently fail (NumCaptures=0).
Changes:
- OpenGLDevice: Add wglCreateContextAttribsARB support for debug context
- OpenGLDevice: Create OpenGL 4.6 core profile with debug flag
- RenderDocCapture: Pass correct window to SetActiveWindow/StartFrameCapture
- OpenGL test: Pass HGLRC via SetDevice(), use BeginCapture/EndCapture
Fix root cause identified via RenderDoc docs analysis:
'For OpenGL it must be the HGLRC, GLXContext, or EGLContext'