[NFC] [Modules] Rename modules related things in Preprocessor and AffectingModules

Rename module related things according to the consensus in
https://discourse.llvm.org/t/rfc-unifying-the-terminology-about-modules-in-clang/66054/
to reduce further confusings.

This only renames things I can make sure. It doesn't  mean all the names
in Preprocessor are correct now.