Further modernize OwnersPackageQuery

Summary:
Ref T8320.

• Add needOwners().
• Split withOwnerPHIDs() [exact owners] and withAuthorityPHIDs() [indirect authority] apart.
• Restore searching by path.

Test Plan: Browsed pacakges, edited packages, edited paths.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T8320

Differential Revision: https://secure.phabricator.com/D13922