CodeGen: selecting a radio option produce invalid code

[passiomatic]

This is caused by the option function signature: https://package.elm-lang.org/packages/mdgriffith/elm-ui/latest/Element-Input#option which produces Option value msg.

We could avoid to generate code for certain nodes, requiring the user to select a different element. That is, if she wants to output an option she needs to select the parent radio.

This is probably handled out-of-the-box by a more type safe generator tool like elm-codegen, see: https://github.com/passiomatic/elm-designer/issues/63