Currently we have a lot of places where we repeat the type `Type<T>|AbstractType<T>|InjectionToken<T>` which makes it cumbersome to add another type or to type something else with the same signature.
These changes add a new type that can be used instead.
Fixes#39792.
PR Close#41580
```
export const __core_private_testing_placeholder__ = '';
```
This API should be removed. But doing so seems to break `google3` and
so it requires a bit of investigation. A work around is to mark it as
`@codeGenApi` for now and investigate later.
PR Close#38274
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
Kristiyan Kostadinov
JiaLiPassion
Misko Hevery
Joey Perrott