ReadonlyMap is a superset of Map, in keyValuePipe we do not change the value of the object so ReadonlyPipe Works right in this case and we can accomodate more types. To accomodate more types added ReadonlyMap in Key Value pipe.
Fixes#37308
PR Close#37311
`KeyValuePipe` currently accepts `null` values as well as `Map`s and a
few others. However, due to the way in which TS overloads work, a type
of `T|null` will not be accepted by `KeyValuePipe`'s signatures, even
though both `T` and `null` individually would be.
To make this work, each signature that accepts some type `T` has been
duplicated with a second one below it that accepts a `T|null` and
includes `null` in its return type.
Fixes#35743
PR Close#36093
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
