gfxwrapper.cmake no longer exists

The first step is broken:

https://openxr-tutorial.com/windows/opengl/1-introduction.html#cmake-and-project-files

> Download the linked file below and put it in cmake. This will be used in our CMakeLists.txt to help build our project.
>
> gfxwrapper.cmake

"gfxwrapper.cmake" is not linked. That file doesn't exist in `cmake`: it was removed in bf99e5ee / #147. It isn't clear how to proceed with the tutorial with this file missing.

Start at the linked Windows OpenGL tutorial section and inspect the current cmake directory alongside the CMakeLists.txt instructions. Confirm how the removal in bf99e5ee/#147 affects the first step, then update the tutorial so it refers only to files that exist and can be followed successfully.

Written by the indexing model from the issue text.