* Consistently use "Google Cloud" where appropriate
* Update GCP docs
This updates the GCP docs to use the new updated fields that will be
present in the next release of the plugin as well as fixes up some
inconsistencies between the GCP docs and other auth method
documentation.
This removes all references I could find to:
- credential provider
- authentication backend
- authentication provider
- auth provider
- auth backend
in favor of the unified:
- auth method
