feat(deriving): deriver like api

[fakenickels]

[@lenses]
[@decco]
type bartux = {
  color: string,
  top: int,
};

let bartux = {color: "red", top: 10};

Js.log(bartux->bartux_get(Color));
Js.log(bartux->bartux_set(Top, 20));
Js.log(bartux_encode(bartux));

It still coexists along side with the module extension