check token permissions on start and exit early #597
Description
Without repo:status permission, for example, lookout produces error like
21T17:31:47.422411061Z" level=error msg="event processing failed" app=lookoutd error="posting analysis failed: github api error: POST https://api.github.com/repos/EgorBu/best-practices-experiments/pulls/6/reviews: 404 Not Found []" event-id=872ad4684e184e8d059e3357565648604c9ec373 event-type=*pb.ReviewEvent head=refs/pull/6/head repo="https://github.com/EgorBu/best-practices-experiments.git"
which is super difficult to understand how to fix. (give more permissions to the token)
We can check token permission when lookout starts to report missing permissions and exit immediately.