SVGHMI: move declaration of "xmlns" javascript const so that widgets can use it.
This was broken in earlier commit, when changing initial execution order because of implementing websocket reconnect.
<?xml version='1.0' encoding='utf-8'?>
<BACnetServerNode xmlns:xsd="http://www.w3.org/2001/XMLSchema" UDP_Port_Number="47808" BACnet_Device_ID="3" BACnet_Communication_Control_Password=" " BACnet_Device_Location="Beremiz lab" Network_Interface="virbr0"/>