Add option to disable wrapping scalajs-react props in Callback

[Lermex]

Scalajs-react added a feature, called Effect Agnosticism, to support arbitrary effects instead of its own Callback and CallbackTo types. For example, you can use Cats Effect or ZIO.

Unfortunately, when scalajs-react is imported in this mode, the Callback classes are not in the same package so the code generated by the Converter doesn't compile. Even if it did, re-wrapping the effect type that you actually use in Callback is even worse than having to unwrap it into an impure function.

Ideally the Converter would support effect-agnostic scalajs-react as a new flavor, but doing so requires outputting higher-kinded type parameters in various places so it's a bit of an undertaking.

As a more immediate solution this PR just adds an option to disable the wrapping of callback-style props in the Callback type so the user could manually unwrap their effect type into impure functions but keep using all the other facilities of the ScalajsReact flavor.