The immediate use case is for testing, where some tests need to use the PHP implementation even when wikidiff2 is installed. Bug: T237049 Change-Id: I41dc4c0933429065d7638f518ec31f0a056afc41
Also move the 'unit' test into integration, given it tests code using globals. Change-Id: Ie039cae9b5d2870c18a6deefec9a73de522dd847