R1:7b567f185c48

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