FIX: fix a bed texture not display issue

1. change default bed_type to "1" in app_config
2. if old app_config.bed_type is 0, change it to 1

Signed-off-by: yifan.wu <yifan.wu@bambulab.com>
Change-Id: I9923187ab480b0a4991bfbc13892bfb43b2a990b

src/libslic3r/AppConfig.cpp

@@ -290,7 +290,7 @@ void AppConfig::set_defaults()
     }
 
     if (get("curr_bed_type").empty()) {
-        set("curr_bed_type", "0");
+        set("curr_bed_type", "1");
     }
 
 #if BBL_RELEASE_TO_PUBLIC