GitHub Checks integration for provisioning

[alecthomas]

We should integrate provisioning with GitHub Checks. This would provide a really nice user experience.

[stuartwdouglas]

It's possible that if you add the Quarkus github extension to an FTL app it will just work and allow you to write a Github app.

One thing to be aware of is that the apps send events to a single URL, so if you wanted this to be a per-cluster thing each cluster would need to register it's own github app. We would probably want to have a central hosted service for this.