Track and publish performance metrics

[jayconrod]

• We need a benchmark that measures how long it takes to build various targets. This should include minimal "hello world programs", various popular Go libraries, and significant targets in Kubernetes. It should measure clean builds and incremental (single file change) builds.
• This benchmark should be run regularly and automatically (likely in a cron job somewhere).
• The results should be published somewhere that's publically visible (a public Google Sheet with a pretty graph would be a minimum viable product).