identitytoolkit does not appear to need an OAuth token

[mwilliammyers]

I don't think any of the identity platform APIs require an OAuth token in the request header...

https://cloud.google.com/identity-platform/docs/use-rest-api#section-verify-custom-token

If that is true, we should probably not require auth in the Client etc. (nor should we even depend on auth crates)...

[mwilliammyers]

Ahh, some of the request options require an OAuth2 token, e.g. using local_id for a GoogleCloudIdentitytoolkitV1SignUpRequest...

I am not entirely sure what we should do, but for now I am more than happy to continue using it as is (sending a token on every request like all of the other clients).