[clang] [C++20] [Modules] Introduce -fexperimental-modules-reduced-bmi (PR #85050)

[Matheus Izvekov via cfe-commits]

https://github.com/mizvekov approved this pull request.

I share the objections that it may be too soon to introduce a driver flag for this. Only a frontend flag is ok for now, but it's non blocking on my side because it doesn't look like it will be particularly hard to deprecate it later.

https://github.com/llvm/llvm-project/pull/85050