Summary: Ref T5245. Updates the project/object edge to use a modern class definition. Moves further toward real edges.
Test Plan: Added projects to some objects, viewed transactions in transaction record.
Reviewers: chad, btrahan, joshuaspence
Reviewed By: joshuaspence
Subscribers: epriestley
Maniphest Tasks: T5245
Differential Revision: https://secure.phabricator.com/D9849
