Add support to use as a Golang library

[grayside]

While a CLI tool is workable for any language's testing, being written in Go means any test implementation written in Go could have a simpler implementation.

Current

Must use the tool as a CLI.

Preferred

In Golang, import the package and run the tool via a function call and a configuration struct. This would preserve the existing CI process for end-to-end tests in the golang-samples repository.

This issue affects two categories in my review of the repository:

• Experience: Does the project provide a good experience to users?