Add a custom unit test engine to check the Celerity map is up to date on CSS/JS changes
Summary: Fixes T15209. See T15209#28447 for why I did things this way.
Test Plan:
- Make sure you have no uncommitted local changes
- Run `arc unit --rev HEAD` (this tells Arcanist to only process uncommitted chanegs and not the changes to the PHP files made in this commit)
- See no output (neither test engine found anything to run)
- Modify a CSS or JS file
- Run `arc unit --rev HEAD`
- See a failure message about the Celerity map being out of date and no other tests having run.
- Modify a PHP file inside `src/`
- Run `arc unit --rev HEAD`
- See the standard suite of tests run as normal.
Reviewers: O1 Blessed Committers, mainframe98, avivey
Reviewed By: O1 Blessed Committers, mainframe98, avivey
Subscribers: avivey, mainframe98, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno
Maniphest Tasks: T15209
Differential Revision: https://we.phorge.it/D26577