ActiveStorage support was added to CKEditor in version 5.1.0. However, we can't upgrade to version 5.0.0 or later because it only supports loading CKEditor via CDN. So we're copying the code related to ActiveStorage instead. I tried to move it to the `vendor/` folder, but couldn't find a way to load it from there and if I found one I wouldn't be sure it'd work on production environments.