Journey Orchestration: add attribute JourneyOrigin to be leveraged by Dynamic Reporting (journey jump feature)

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

https://github.com/adobe/xdm/blob/master/extensions/adobe/experience/campaign/orchestration/eventid.schema.json

## What are examples of products that are impacted by the issue

Journey Orchestration, Customer Journey Management

Start with extensions/adobe/experience/campaign/orchestration/eventid.schema.json and review its existing attribute definitions and related schema conventions. Confirm the expected type, placement, and semantics of JourneyOrigin with the Journey Orchestration and Customer Journey Management use cases; done means the schema contains a validated attribute that supports the journey jump feature.

Written by the indexing model from the issue text.