xmlimport change datatype field default

The default DataType of a struct field should be i=24 -> BaseDataType.
Found this error in Opc.Ua.Plastics.Rubber.GeneralTypes

asyncua/common/xmlparser.py

@@ -76,7 +76,7 @@ class NodeData:
 
 class Field:
     def __init__(self, data):
-        self.datatype = data.get("DataType", "")
+        self.datatype = data.get("DataType", "i=24")  # Default is BaseDataType
         self.name = data.get("Name")
         self.dname = data.get("DisplayName", "")
         self.optional = bool(data.get("IsOptional", False))