[php-src] Issue #14889: Commands execution from php, idea(s) how to restrict from code consumer's scope

Issue: https://github.com/php/php-src/issues/14889 Author: devnexen ### Description The original discussion stemmed from [there](https://externals.io/message/124296). Basically how to, more effectively, restrict php process user access to system commands. Albeit the implementation idea had been rejected, for valid reasons, it should not stop to improve in this area. Note that calls like execvP allows to enforce specific search paths but is even less standard than execvpe.