[FEATURE] Create factory class for Workflow Steps

[dbwiddis]

Is your feature request related to a problem?

Continuation of work started in #26.

While parsing a template, we create a ProcessNode that will manage the actual execution of the WorkflowStep with some optional initial WorkflowData. There is a placeholder conditional doing this for a demo "create index" step, but this needs to be more scalable.

What solution would you like?

1. Add two fields to the nodes in the template:
   • one identifies the class type to generate.
   • one identifies input data needed.
2. Pass this class type string to a factory class that creates an instance of the corresponding class.
3. Parse the input data field (if any) to generate a WorkflowData anonymous subclass.
4. Use these elements when instantiating a ProcessNode.

What alternatives have you considered?

Several more complex ways of handling it such as using injection, reflection, pre-parsing the template to populate a map, etc. Since multiple nodes may share the same class type, singletons or map lookups won't work.

Do you have any additional context?

We may iterate over this design and modify it later, but it seems the best direction to start wtih.