[clang] [clang][Darwin] Remove legacy framework search path logic in the frontend (PR #138234)

[Ian Anderson via cfe-commits]

ian-twilightcoder wrote:

This is a takeover of https://github.com/llvm/llvm-project/pull/120149 because Louis is out, I'm not a maintainer so I can't push to his fork, and I redid most of it anyway.

https://github.com/llvm/llvm-project/pull/138234