Update Journey Version Step Events XDM Mixin to add attributes related to CJM reporting

## What are the schemas that are affected by the issue

https://github.com/adobe/xdm/blob/master/extensions/adobe/experience/journeyOrchestration/stepEvents/journeyStepEventCommonFieldsMixin.schema.json

What are examples of products that are impacted by the issue
Journey Orchestration, Customer Journey Management

Start by reviewing extensions/adobe/experience/journeyOrchestration/stepEvents/journeyStepEventCommonFieldsMixin.schema.json. The issue does not enumerate the CJM reporting attributes or their expected values, so confirm the required fields and examples with maintainers before changing the schema. Done means the agreed attributes are represented in the mixin for Journey Orchestration and Customer Journey Management.

Written by the indexing model from the issue text.