Hide Code Runner button for .dart files if Dart extension is also installed

Hi!

I work on the [Dart extension](https://marketplace.visualstudio.com/items?itemName=Dart-Code.dart-code) for VS Code. I've recently added buttons to make running/debugging Dart files more discoverable (based on recent [VS Code recommendations](https://code.visualstudio.com/updates/v1_47#_single-file-debugging)) though uses with Code Runner installed now see multiple sets of buttons that can be confusing:

For Flutter users, the Code Runner button won't work correctly (since it only calls `dart ` but Flutter projects need to be run with `flutter`) whereas the Dart buttons are contextual and will work for both Dart and Flutter projects (as well as test files and others).

Would you consider hiding the button for Dart files if the Dart extension is also installed, to avoid some confusion?

Thanks!