Add OpenGL quad integration test with texture mapping
- Add tests/RHI/OpenGL/integration/quad/ with main.cpp, CMakeLists.txt
- Add GLSL shaders (quad.vert, quad.frag) for textured quad rendering
- Use OpenGLVertexArray, OpenGLBuffer, OpenGLShader, OpenGLPipelineState
- Add OpenGLTexture::LoadFromFile for texture loading (earth.png)
- Add OpenGLSampler for texture sampling configuration
- Disable depth test for 2D quad rendering
- GT.ppm generated from OpenGL rendering output (0% diff on re-run)
ssdfasd
11919aad2f
