Property of inputs and outputs should be a path

[forman]

The property name field of callback inputs and outputs should be normalized to a property path.

export interface InputOutput {
  kind: InputOutputKind;
  id?: string;
  property: string[];  // A path now!
}

Hence, when the UI receives a name from the server, it should be normalized using input = {...input, property: input.property.split(".")}.

After the change, we should only use property using get/set as provided by https://github.com/mariocasciaro/object-path.