Once the conversion is done, I think we should

1. Move code from FlutterPlugin and FlutterPluginUtils which is responsible for adding tasks to a gradle Project to a FlutterPluginTaskAdder or similar, to encapsulate it all in one place.
2. Do the same for code that interacts with plugins, to a PluginConfigurer or similar.

As those are both logical pieces that can be removed (and in particular which don't belong in a monolithic FlutterPluginUtils class).