quickSettings: Fix icon-name construct property in menu toggles
Both :icon-name and :gicon are propagated to the internal QuickToggle with property bindings. However the bindings are set up in the wrong order:
:icon-name is a convenience property to set :gicon to a ThemedIcon of the given name. That means binding :icon-name first will correctly set the underlying StIcon's :gicon, but then the :gicon binding will set it again to null.
Fix this by swapping the order in which the bindings are set up, so that it works for both properties.
Fixes #6542 (closed)