[lld-macho] Implement -load_hidden

This flag was introduced in ld64-609. It instructs the linker to link to
a static library while treating its symbols as if they had hidden
visibility. This is useful when building a dylib that links to static
libraries but we don't want the symbols from those to be exported.

Closes #51505

Differential Revision: https://reviews.llvm.org/D130473