colorize-svg.js must support the same configuration format as MediaWiki's ResourceLoaderImageModule. They have diverged since their creation, and that's blocking us from easily reusing the definitions. ResourceLoaderImageModule's format is better.
Most of the work is done, but the way we do ltr/rtl versions of icons is awful. T94560: Properly support ltr/rtl icon versions in colorize-svg.js tracks that. I think this is the last blocker left.