Pass bind_detect's Result to Python by Reference

pybind11 copies a reference argument to an override, so a Python
printer agent that filled in detect wrote to a throwaway object and the
host always saw an empty detectResult. Pass it as a pointer so Python
edits the caller's struct.

src/slic3r/plugin/pluginTypes/printerAgent/PrinterAgentPluginCapabilityTrampoline.hpp

@@ -69,7 +69,8 @@ public:
 
     int bind_detect(std::string dev_ip, std::string sec_link, detectResult& detect) override
     {
-        ORCA_PY_AGENT_OVERRIDE(int, bind_detect, dev_ip, sec_link, detect);
+        // Passed as a pointer: pybind11 copies a reference argument, so the plugin's writes would be lost.
+        ORCA_PY_AGENT_OVERRIDE(int, bind_detect, dev_ip, sec_link, &detect);
     }
 
     std::string get_user_selected_machine() override