gallium driver refactoring

Hi,

I'm working on some big refactorings for gallium to improve CPU
performance. The first MR can be found here:

https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33813

If applicable, please review and sign off within the next couple days.
Given the speed with which mesa moves, I'd like to get this merged by
end-of-week to avoid conflicts.


Thanks,
Mike