reject scxml documents with raise and no @event at parse time

[mattoshry]

https://www.w3.org/TR/scxml/#raise

<scxml xmlns="http://www.w3.org/2005/07/scxml"
  version="1.0" name="error-raise-event">

<state id="uber">
  <transition event="*" target="fail">
    <!-- missing @event -->
    <raise/>
  </transition>
</state>

<final id="fail"/>

</scxml>```