Request for Auto-Formatting of Generated Code

[K9i-0]

The code generated by slang currently shows differences when formatted with dart format ..

I want it to auto-format like in packages using source_gen, like freezed. They use DartFormatter from the dart_style package. Using DartFormatter the same way should work. https://pub.dev/packages/dart_style#using-the-dart_style-api

Similar to Issue #163