Setup with ffi Preload for better security

Because PHP does not have built in WASM support we use the Extism binary to execute the WASM. This happens through the Fourign Function Interface (FFI) allowing PHP to use external C libraries. The easiest way to allow this is to set `ffi.enable=true` in the php.ini file. This is a potential security vulnerability if another plugin or theme in the Wordpress installation is compromised. It would be better to set `ffi.enable=preload` and explicitly allow only the extism binary to access the FFI it needs.