Make owners typeahead mostly reasonable

Summary: Ref T8320. Fixes T8427. This is still a little funky because Owners has weird name rules, but should fix the bugs (unselectable packages) in T8427.

Test Plan: Browsed Owners typaheads, used various search functions.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T8320, T8427

Differential Revision: https://secure.phabricator.com/D13349