Resolve "Create an alerter that can output a message to the console"
Closes #6 (closed) by introducing a class that can output a message to the console when an MR referencing a confidential issue is detected.
I created https://gitlab.com/gitlab-com/gl-security/appsec/tooling/confidential-issue-detector-test-project/project to get some real end-to-end local testing which revealed a few bugs, too.
Example:
