Draft: IVE: Load UUID from xml file as attributeChanged

Closes #877

src/libs/ivcore/resources/iv_system_attributes.xml

-<Attrs version="1.0">
+<Attrs version="1.1">
+    <Attr label="id" name="id" visible="false" editable="false">
+        <Type>
+            <String validator="\{[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}\}"/>
+        </Type>
+    </Attr>
     <Attr label="Name" name="name">
         <Type>
             <String validator="[a-zA-Z][a-zA-Z0-9_]*"/>