Summary:
Ref T10748. Ref T10366. This adds a new EditEngine, EditController, Editor, Query, and Transaction for RepositoryURIs.
None of these really do anything helpful yet, and these URIs are still unused in the actual application.
Test Plan: {F1249794}
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T10366, T10748
Differential Revision: https://secure.phabricator.com/D15815
