Support for past entity instead of just old state value inside state validator function param

[r1jsheth]

Currently inside the function annotated with @TransitionValidator

fun functionName(id: Long, oldVal: Any, newVal: Any) {
    // oldVal is just the field
    // if we want to parse the whole entity, we can not
    // we can have the function as the following instead
    // fun functionName(id: Long, oldVal: Object, newVal: Object)
    // where we get the whole past snapshot of the object, which we can not query via DB.
}