Reland '[TextAPI] Add DylibReader' (#75862)

> Add support for reading binary Mach-o dynamic libraries. It uses
libObject APIs for extracting information relevant to TAPI and tbd
files. This includes but is not limited to load commands encode data
like install names, current/compat versions, and symbols.

This originally broke because DylibReader uses Object and Object depends
on TextAPI. Breaking this up in a nested library prevents this cycle.