* Enable ANGLE's desktop GL backend
Only the D3D and GLES backends were available, but getting desktop GL to
work is trivial.
The Vulkan backend would be a much bigger task, unfortunately.
* x-add-version
Co-authored-by: Billy Robert O'Neal III <bion@microsoft.com>
* Avoid exluding EGL/eglext_angle.h from ANGLE and add egl_loader_autogen.cpp/h that were not properly added.
* Add port version to ANGLE port.
* Ran vcpkg x-add-version --overwrite-version angle.