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'?>
<BeremizRoot xmlns:xsd="http://www.w3.org/2001/XMLSchema" URI_location="LOCAL://">
  <TargetType/>
  <Libraries Enable_SVGHMI_Library="true"/>
</BeremizRoot>