On prop init actions

When prop is initialized, you can do some extra work via onInit interface.

Parameters	Type	Description
event	string
value	JsfValueOptionsType	Check Value Options for description.

onInit?: (
    {
      type: 'set',
      value: JsfValueOptionsInterface
    } |
    {
      type: 'eval',
      $eval: string
    }
    )[];