Email body should contain a summary of 979 dag runs that were successes and failures. For the failures, we want a link to the dag run so we can go to airflow and investigate.

The summary for successful adding of 979 fields should include a total count of instances that had 979s added.

Failures: when a MARC record failed to update, include the instance ID and the 979 field (if accessible at this point in the dag).

When dag runs are triggered from the UI or the find instances DAG, send the dag run ID's to the polling DAG.