[lld-macho] Handle framework search path, alongside library search path

Summary:
Add front-end support for `lld::macho::Configuration::frameworkSearchPath`.

Depends on D80582.

Reviewers: ruiu, pcc, MaskRay, smeenai, int3, Ktwu, alexshap, christylee

Reviewed By: int3

Subscribers: ormris, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D80677