Fix generating default values for StringName

Cases other than `&""` were not processed correctly

(cherry picked from commit 6cd6c8923a)

binding_generator.py

@@ -2321,6 +2321,8 @@ def correct_default_value(value, type_name):
         return f"{type_name}()"
     if value.startswith("Array["):
         return f"{{}}"
+    if value.startswith("&"):
+        return value[1::]
     return value