[clang] [clang-cl] Add new option `/pathmap:<from>=<to>` to replace the path prefix <from> with <to>. (PR #198664)

[Vladimir Vereschaka via cfe-commits]

vvereschaka wrote:

got `cl-pathmap` tests failures on [llvm-clang-aarch64-darwin](https://lab.llvm.org/buildbot/#/builders/190)
https://lab.llvm.org/buildbot/#/builders/190/builds/43598
Reverting.

https://github.com/llvm/llvm-project/pull/198664