fix(v8 ResizeGroup): Add accessible name to overflow button (#34974)

Author: emmayjiang

packages/react-examples/src/react/ResizeGroup/ResizeGroup.OverflowSet.Example.tsx

@@ -107,7 +107,7 @@ export const ResizeGroupOverflowSetExample: React.FunctionComponent = () => {
   };
 
   const onRenderOverflowButton = (overflowItems: any) => (
-    <CommandBarButton role="menuitem" menuProps={{ items: overflowItems! }} />
+    <CommandBarButton aria-label="more" menuProps={{ items: overflowItems! }} />
   );
 
   const onRenderData = (data: any) => {

packages/react-examples/src/react/ResizeGroup/ResizeGroup.VerticalOverflowSet.Example.tsx

@@ -61,6 +61,7 @@ const onRenderItem = (item: any) => (
 
 const onRenderOverflowButton = (overflowItems: any) => (
   <CommandBarButton
+    aria-label="more"
     styles={buttonStyles}
     menuIconProps={{ iconName: 'ChevronRight' }}
     menuProps={{ items: overflowItems!, directionalHint: DirectionalHint.rightCenter }}