TLDR: Reinforce the Google C++ Style Guide recommendation for using references for output parameters; or explicitly recommend pointers for outputs.

The Server Code Style currently defaults to the Google C++ Style Guide in areas where we do not provide any explicit guidance.

The guidance for Inputs and Outputs currently recommends using references for output parameters. This is a recent shift from the version of the style guide most of the MongoDB codebase was written against. The guidance before this change in the Google style guide was to use pointers for output parameters.