When an entity gets reported, save a copy that can't be edited

To increase the validity of the jury and moderation process, we need to create a historical record of the entity when it gets reported. Currently, reports can be edited and the offending content can be removed and invalidate our three strike process.

• When an entity is reported, save a copy of the original entity to the moderation_reports_by_state table in cassandra
• Extend the https://www.minds.com/api/v2/moderation/jury/initial endpoint to return the copy of the original entity
• Keep the new entity URN as we'll be showing them side by side
• Unit tests to make sure our repository and manager return the right thing