Migrate "PhabricatorOwnersPackageCommitRelationship" to "PhabricatorRepositoryAuditRequest"

Summary:

• Move table to Repository, since we have no Owners joins in the application anymore but would like to do a Repository join.
• Rename "packagePHID" to "auditorPHID", since this column may contain package, project, or user PHIDs.

Test Plan:

• Browsed Owners, Audit, and Differential interfaces to the Audit tool.
• Made comments and state changes.
• Ran "reparse.php --herald --owners" on several commits.

Reviewers: btrahan, jungejason

Reviewed By: btrahan

CC: aran, epriestley, nh, vrana

Maniphest Tasks: T904

Differential Revision: https://secure.phabricator.com/D1787