Add pagination logic to fetch all timeline events

Created by: eseliger

Fixes values derived from events on busy PRs by using the pagination info from GraphQL to receive all pages of items. This happens when a PR has a lot of comments or a lot of commits in it, and this should ultimately fix it. I think we don't need to worry about running into rate limits, because it only happens to have so many events very rarely. (But it happened on our own repo!)

Closes #11744 (closed)