Automated linting at the repo level

[fpcorso]

There are multiple actions/bots that can scan a GitHub repo and create issues when code doesn't pass linting. However, we probably don't want to turn this on until we have properly set up all of our linting and started making changes.

An example bot is: https://github.com/humanmade/linter-bot

This was originally a sub-task of #822

[danieliser]

@fpcorso I love this idea, and yea agree we don't want a flood of issues so punt this til we have tidied already.