Provide a way to print what file or files triggered a rebuild in watch mode

[nfachan]

Specific Maelstrom Program?
All test runners.

Problem Statement
If the test runner keeps rebuilding and re-running tests, it may be hard to figure out why. While debug output can be turned on, it's overwhelming and hard to sift through.

Proposed Solution
There should be a boolean configuration value that can be used to tell the test runner to print out messages about why it's restarting.

The messages should also explain when editors saves and whatnot take too long and miss the debounce window. It can be confusing to see that a path triggered a restart, and then see it restart twice.