Include `step_type_name` in structured data

Structured data should include `step_type_name` in addition to `step_type` as otherwise it is difficult to pull apart different steps from within the cycle once it has been structured. Should be included as a new entry in `structured_dtypes.yaml` and should not affect other cyclers. 

I.e., if the incoming dataframe has `step_type_name` then keep it in the structured dataframe. Otherwise, don't