Add dangerbot to enable reviewer roulette

What does this MR do?

Adds danger. My main idea is to add the reviewer roulette for pages to spread review load more evenly among reviewers/maintainers.

TODO

• I added the Changelog trailer (e.g. Changelog: added) to the commits that need to be included in the changelog
• I added unit tests or they are not required
• I added acceptance tests or they are not required
• I added documentation (or it's not required)
• I followed code review guidelines
• I followed Go Style guidelines