This series begins the process of moving GL format detection code to a separate file, for reasons described in 1/6 and [1].
Still, if this is deemed undesirable or not worthwhile, I don't particularly mind dropping this and/or further refactoring work. At this point my initial goal, viz. to find all of the code in wined3d that implicitly assumes it's running under the GL backend, has basically been accomplished.
[1] https://gitlab.winehq.org/wine/wine/-/merge_requests/3238