[clang] [Clang][Driver] Add option to provide path for multilib's YAML config file (PR #109640)

[Victor Campos via cfe-commits]

vhscampos wrote:

LGTM from the Arm target perspective, but not sure about the impact on the workflow of other targets. I suggest this waits for others' reviews.

https://github.com/llvm/llvm-project/pull/109640