Context: [Deprecating GTMFetcherAuthorizationProtocol in favor of new GTMSessionFetcherAuthorizer](https://github.com/google/gtm-session-fetcher/pull/315) Solution: We should replace the protocol type of `fetcherAuthorizer` in GIDGoogleUser API.
Context:
Deprecating GTMFetcherAuthorizationProtocol in favor of new GTMSessionFetcherAuthorizer
Solution:
We should replace the protocol type of
fetcherAuthorizerin GIDGoogleUser API.