PHP Pitfalls: mention strlen() deprecation since PHP 8.1
Summary:
- expand documentation about PHP Pitfalls to mention strlen() in PHP 8.1
- mention phutil_string_cast()
- mention phutil_nonempty_string()
- add a commodity link from PHP Contributors Manual
Ref T15190
Test Plan: * check with your big eyes for typos
Reviewers: O1 Blessed Committers, Cigaryno, avivey
Reviewed By: O1 Blessed Committers, Cigaryno, avivey
Subscribers: speck, tobiaswiese, Matthew, Cigaryno
Tags: #documentation
Maniphest Tasks: T15190
Differential Revision: https://we.phorge.it/D25108