[clang] [clang][ModulesDriver] Add support for Clang modules to -fmodules-driver (PR #187606)

[Qiongsi Wu via cfe-commits]

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

Thanks! Overall LGTM! I have two inline comments. 

https://github.com/llvm/llvm-project/pull/187606