CodeGen: rewrite module using elm-codegen

Recently released [elm-codegen][1] package  will help greatly to avoid to produce code that doesn't compile. 

The idea is to generate the bindings for the Elm-ui package, add to this repo, and make it straightforward for the Elm compiler to check for any mismatched type.

[1]: https://package.elm-lang.org/packages/mdgriffith/elm-codegen/latest/