fix(grid): address null TypeError on focusing a grid with no data and column headers - master#16520

kacheshmarova merged 4 commits intomasterIgniteUI/igniteui-angular:masterfrom

bpachilova/ariaHidden-header-groups-fix-16517IgniteUI/igniteui-angular:bpachilova/ariaHidden-header-groups-fix-16517Copy head branch name to clipboard