WS-2898: Write tests for wf_monitor

This adds unit tests for wf_monitor so it is at 100% test coverage. Documentation on the tool, how to use it, and how to run tests can be found in the updated README.

Most of the new code was written by AI; specifically by Claude Haiku 3.5 and Claude 3.7 Sonnet.

Also, the previous empty test (and the file it was in), as well as some old test data, have been removed. Some style changes have been made to monitor.py.

This Confluence document lists takeaways from my work, my messages to and responses from the AI model, and other notes describing the development process.