[clang] [Modules] Add -cc1 -flate-module-map-file to load module maps after PCMs (PR #88893)

[Jan Svoboda via cfe-commits]

https://github.com/jansvoboda11 approved this pull request.

Thanks for the explanation! This LGTM, but I agree with the sentiment that I'd be nice to have this as the default behavior. Any effort towards that would be appreciated!

https://github.com/llvm/llvm-project/pull/88893