Add GitHub Action to test and compile binaries

[jamesaoverton]

It would be nice to attach binaries for at least Linux to the GitHub Action results, but I'm still not sure the best way to do this.

As I said in #7, I'm starting to think that a plain GitHub Action calling a make test is better than a fancy custom GitHub Action. One benefit is that you can run make locally, while it's hard to replicate a GitHub Action environment. Debugging GitHub Actions is particularly painful.

[ckindermann]

There are GitHub Actions for comparing the output of command line calls with text files, e.g., this. I haven't found one that actually works yet.