[Driver] [C++20] [Modules] Support -fmodule-output= (2/2)

The patch implements `-fmodule-output=`. This is helpful if the build
systems want to generate these output files in other places which is not
the same with -o specified or the input file lived.

Reviewed By: dblaikie, iains

Differential Revision: https://reviews.llvm.org/D137059