Towards https://github.com/flutter/flutter/issues/160692. Prior to `flutter_template_images: 4.3.0`, the `app_shared` directory was required. In 4.3.0 it was forked back out to `app` (https://pub.dev/packages/flutter_template_images/changelog), as the `skeleton` template has been removed, and the `skeleton` template was the (only) reason for `app_shared` (to share code between `app` and `skeleton`). This is a NOP change tested by existing tests.