[lld] Add --lto-debug-pass-manager option

Add support for printing the passes run for LTO.

Both ELF and COFF have `--lto-debug-pass-manager` (`-ltodebugpassmanager`) to print the compiler passes run during LTO. This is useful to check that a certain compiler pass is run in a test, e.g., https://reviews.llvm.org/D151589

Reviewed By: #lld-macho, MaskRay, int3

Differential Revision: https://reviews.llvm.org/D151746