Fix a PHP 8.1 deprecated use of strlen with a NULL argument on commit page master
Summary: With PHP 8.1+ it is not possible to view a commit if the author field is not properly defined Indeed, if the commit author is not properly defined, strlen(null) is called, causing a deprecation warning, elevated to exception. Using strlen() to check string validity is deprecated since PHP 8.1. Phorge adopts phutil_nonempty_string() as a replacement. Fix T15628 Test Plan: - Push a new commit on a subversion repository (since T15629 is not yet addressed) - Visualize the commit - You should not get a RuntimeException Reviewers: O1 Blessed Committers, Sten, valerio.bozzolan Reviewed By: O1 Blessed Committers, Sten, valerio.bozzolan Subscribers: Sten, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno Maniphest Tasks: T15628 Differential Revision: https://we.phorge.it/D25422