[clang] [flang] [llvm] [llvm] Lift VFS from `PGOOptions` to `PassBuilder` (PR #160188)

[Steven Wu via cfe-commits]

https://github.com/cachemeifyoucan commented:

LGTM in general. 

Nit: I will title the commit to be add VFS to PassBuilder so LLVM passes can access file through VFS, and lifting PGO option is just one use case for that.

https://github.com/llvm/llvm-project/pull/160188