[C++20] [Modules] Don't ignore -fmodule-file when we compile pcm files

Close https://github.com/llvm/llvm-project/issues/62843.

Previously when we compile .pcm files into .o files, the
`-fmodule-file=<module-name>=<module-path>` option is ignored. This is
conflicted with our consensus in
https://github.com/llvm/llvm-project/issues/62707.