This change is part of a larger effort to migrate all golden type
tracking files to a single location. Additionally, this makes it
a bit easier to manage file ownership in pullapprove.
PR Close#36455
Moves the public api .d.ts files from tools/public_api_guard to
goldens/public-api.
Additionally, provides a README in the goldens directory and a script
assist in testing the current state of the repo against the goldens as
well as a command for accepting all changes to the goldens in a single
command.
PR Close#35768
Joey Perrott