Manual roll of the ICU library. This normally happens automatically, but this time around, ICU folks changed their license, so that needs to be fixed up. I wish they would stop doing that. :) This manual change should enable us to turn the auto-roller back on. https://github.com/flutter/flutter/issues/149684 [C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style