Add Badges to UserCache

Summary: Ref T12270. Builds out a BadgeCache for PhabricatorUser, primarily for Timeline, potentially feed? This should still work if we later let people pick which two, just switch query in BadgeCache.

Test Plan: Give out badges, test timeline for displaying badges from handles and without queries. Revoke a badge, see cache change.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12270

Differential Revision: https://secure.phabricator.com/D17503