Add support for GitHub Project automation

[andreilgeorgescu]

At the moment, it's very difficult to automate GitHub Project items.

For example, if I have a Github Project Item that is associated with an issue, and that issue is associated with a pull request. I would like it that when my pull request fails a status check, that the PR's associated issue's associated project item's status is changed to "Triage".

There do not seem to be any tools to assist with this other than dealing with the GraphQL API directly. Mergify seems like it would be perfectly suited to tackle this if it had a closer integration with the GitHub Project API.