[TextAPI] TBD Reader/Writer
Add basic infrastructure for reading and writting TBD files (version 1 - 3).
The TextAPI library is not used by anything yet (besides the unit tests). Tool
support will be added in a separate commit.
The TBD format is currently documented in the implementation file (TextStub.cpp).
Update: This contains changes to fix issues discovered by the bots:
- add parentheses to silence warnings.
- rename variables
- use PlatformType from BinaryFormat