[R] Test GCS auth with gargle/googleAuthR

These are the main packages that let folks worth with Google Cloud from R, so we should make sure we can play nicely with their auth methods, how they cache credentials, etc.

**Reporter**: [Neal Richardson](https://issues.apache.org/jira/browse/ARROW-16880) / @nealrichardson

_{**Note**: *This issue was originally created as [ARROW-16880](https://issues.apache.org/jira/browse/ARROW-16880). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

No repository files, tests, or entry points are named. Start by reviewing the R package's current Google Cloud Storage authentication and credential-caching paths, then assess gargle and googleAuthR; done means test coverage demonstrates compatibility with their authentication methods and caching behavior.

Written by the indexing model from the issue text.