ENH: calib support multi_extruder

1. backend support multi_extrude data structure
2. Compatible with third-party calibration
3. fix bug when get extruder in gocde export process

Change-Id: I5dac9abdd9907a521a1ba9b480f9e05640591bc1
(cherry picked from commit 21e6271e59ea8e4924866275566617d14a4b2b6e)

src/slic3r/GUI/DeviceManager.hpp

@@ -541,6 +541,7 @@ public:
 
     std::string product_name;       // set by iot service, get /user/print
 
+
     std::string bind_user_name;
     std::string bind_user_id;
     std::string bind_state;     /* free | occupied */