Added DslFactory

Allow typed access to JobParent through an interface for DSL script helper classes and to ease unit testing of those.
in this example, the name of the object in the DSL context appears to have been changed, but I don't see anywhere in the run context with a similar change to make this actually true. That is to ask, in my helper library should I continue referencing `jobFactory` or change those references to `dslFactory`?