in previous versions of this widget, the calls that are available due to
inheritance did not work. efl_ui_check_selected_set did not work on a
radio button. However, the internal function _state_set did just exactly
that. So this commit refactors the activity emitting out of the
function, so the _state_set function can just be used as the
efl_ui_check_selected set function.

Depends on D9058