[llvm][llvm-nm] add TextAPI/MachO support

Summary:
This completes the needed glueing to support reading tbd files from nm.
This includes specifying which slice filtering with `--arch` and a new
option specifically for tbd files `--add-inlinedinfo` which will show
the reexported libraries that are appended in the tbd file.

Reviewers: ributzka, steven_wu, JDevlieghere, jhenderson

Reviewed By: JDevlieghere

Subscribers: hiraditya, MaskRay, dexonsmith, rupprecht, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81614