guf-image: Add the guf-show-demo to the guf-image

Add the guf-show-demo QML based trade show demonstration tool to the
standard guf-image.

It installs itself as an autostart tool dependent of weston and started
by the systemd init system.

BCS 746-000079

recipes-bsp/images/guf-image.bb

@@ -32,6 +32,7 @@ IMAGE_INSTALL_GRAPHICS += " \
     "
 
 IMAGE_INSTALL_GUF += " \
+    guf-show-demo \
     packagegroup-guf-small \
     "