Add support for chrooted php-fpm, implements #3220
This PR adds a checkbox in Site options to enable/disable chrooted PHP-FPM. Note that:
- server variables DOCUMENT_ROOT, HOME and SCRIPT_FILENAME are not corrected for apache+mod_fastcgi, because that is not supported by mod_fastcgi
- certain PHP functionalities require things to be available within the chroot. Eg if you work with
date()
, the chroot will need /usr/share/zoneinfo