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.
<xsd:element name="Xenomai">
<xsd:complexType>
%(toolchain_gcc)s
<xsd:attribute name="XenoConfig" type="xsd:string" use="optional" default="xeno-config"/>
</xsd:complexType>
</xsd:element>