- extract _add_driver_radiobutton_list from existing code
 - refactor it to allow it to be called repeatedly while reusing widgets
 - make some private Netlist functions public as they are used elsewhere :/
 - eliminate duplicated nets (low-hanging workaround) for a nuisance
   of _get_net_connections().
 - add FIJISearchWidget to the dialog and call _add_driver_radiobutton_list
   from its callback after filtering the driver list