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="ISO-8859-1" ?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xhtml="http://www.w3.org/1999/xhtml">
<xsd:element name="Python">
<xsd:complexType>
<xsd:annotation>
<xsd:documentation>Formatted text according to parts of XHTML 1.1</xsd:documentation>
</xsd:annotation>
<xsd:sequence>
<xsd:any namespace="http://www.w3.org/1999/xhtml" processContents="lax"/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>