Automate updating deprecation-workflow.js

Is it possible to automate what this addon provides even further? For example, we could [write test output to a log](https://github.com/narayanpai/testem-log-reporter), run `flushDeprecations()` against that log, and then diff against the existing `deprecation-workflow.js` to add newly discovered deprecations.

This could be a huge improvement to utilize as part of an upgrade workflow. After running ember-cli-update, you just trigger a script in this addon that automatically updates its own config based on deprecations triggered by your project's tests.