Code monitors: Optionally include results in Slack messages
Created by: camdencheek
This updates slack messages to include results when the user opts in to that.
Fixes https://github.com/sourcegraph/sourcegraph/issues/31174
Without results, we just give the number of matches. Once we have a history page, we will provide a link to that page to view the results.
With results, we also include the firs few matches:
Test plan
Covered by unit tests