Rename PhabricatorUIExample subclasses for consistency
Summary: Ref T5655. Basically, rename all PhabricatorUIExample subclasses to be either Phabricator*UIExample or PHUI*Example.
Test Plan: arc lint and arc unit.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin, epriestley
Maniphest Tasks: T5655
Differential Revision: https://secure.phabricator.com/D11177