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
Adds a new feature to ts-api-guardian allowing for automatically discovering all
entry point d.ts files from all package.json files in a provided directory.
PR Close#35691
Also use it to test the public API for core and common
Once we have an ng_package for every package, we can remove
the npm dependency on ts-api-guardian and the gulp-based
public api check.
PR Close#22544
