Column filter, header row
Turn on header row by given 2 options
  Map opt = {
     'showHeaderRow': true,
     'headerRowHeight': 25
  };
          
Add handler to render header cell
  sg.onHeaderRowCellRendered.subscribe((cj.EventData e,Map args) {
    Element headerEl=  args['node'];
    headerEl.children.clear();
    cj.Column col  = args['column'];
    InputElement inputEl= new InputElement();
    inputEl.dataset['columnId'] = col.field;
    headerEl.append(inputEl);
    inputEl.onKeyUp.listen( (KeyboardEvent ke){
            data.setKeyword(col.field,inputEl.value);
            sg.invalidate();
      });
  });