WGLWindow: Add support for color spaces. Add WGL_ARB_pixel_format and WGL_EXT_colorspace to generate_loader.py. Call wglChoosePixelFormatARB from WGL_ARB_pixel_format and use enums from WGL_EXT_colorspace. Fall back to ChoosePixelFormat if wglChoosePixelFormatARB is not available or does not find a format. Bug: angleproject:6366 Change-Id: I900f6fd6ee0501d5343f21c303b40f1347a53765 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3181720 Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Lubosz Sarnecki <lubosz.sarnecki@collabora.com>