Using a function to set a kit matcher is much easier that crating a new
class. It also enables an easy way to reuse classes that are using it.
E.g.
DeviceProcessesDialog processDialog;
processDialog.kitChooser()->setKitMatcher([](const Kit* kit) {
   return kit->isValid() && other_checks_with(kit);
});

Change-Id: I4e2fc7c52038902412cec5331504230bb8160ceb
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>