When a multiselected light/camera icon is clicked without ctrl pressed,
it now ends up as the single selection as it is supposed to instead
of clearing the entire selection.
Change-Id: Id785cc4cd4ed6100b9bde625e9ccb45646e43b7f
Fixes: QDS-1353
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>