MQTT: remove standalone MQTT clien generator code.
Code was inherited from OPC-UA extension, but not properly maintained.
<?xml version='1.0' encoding='utf-8'?>
<BeremizRoot xmlns:xsd="http://www.w3.org/2001/XMLSchema" URI_location="PYRO://127.0.0.1:61284">
<TargetType/>
<Libraries Enable_SVGHMI_Library="true"/>
</BeremizRoot>