Add new column to PrivateProjectReport table for EF username

In the new reports table, there is a field that indicates user ID. This field at the moment stores the user's Gitlab numeric ID rather than the EF username which would be more useful for context when viewing the report. We need to keep the Gitlab numeric ID to help with a lookup in the table on updates, but otherwise, you need to do additional queries by hand to make the data useful/usable. We should add a new ef_username column that takes the Gitlab username (rather than ID) and stores it in the record for improved usability.