[lld/mac] ad-hoc sign dylibs and bundles on arm64 by default, support -(no_)adhoc_codesign flags

Previously, lld/mac only ad-hoc codesigned executables on arm64.

Matches ld64 behavior. Part of PR49443. Fixes 14 of 17 failures when running
check-llvm with lld as host linker on an M1 MBP.

Differential Revision: https://reviews.llvm.org/D97994