Support for PHP 7.4 shell-less commands

[g105b]

Here is the changelog for 7.4: https://github.com/php/php-src/blob/PHP-7.4/UPGRADING#L323

A problem that has been encountered within this repository is when executing sub-scripts. If a new script is executed, its PID has to be held reference to so that it can be manually killed if the script dies. If the program crashes, it's possible to leave zombie processes running.

Starting a process using the array syntax removes the sub-shell execution, allowing PHP to properly maintain its child processes.

[g105b]

Implemented. Pass either a string or an array of strings.