Proposal: make Go snippets runnable

### Description

We have gotten doc feedback issues complaining that the Go snippets are not readily copy-paste-runnable when written using the current guidelines. I'm not convinced that there is a better approach we could take, but filing an issue for discussion.

### Impact

New guidelines could make it easier for users (especially newbies to Go) to run sample code files directly, or be able to paste it more easily into a main func.

### Challenge

Potentially this could introduce even more cruft into snippet-type samples which are already quite long to include imports, client initialization and cleanup, etc, negatively impacting clarify for doc readers.