Add accessibility add on to storybook for finding a11y issues

Signed-off-by: Philipp Hugenroth <philipph@spotify.com>

packages/core-components/src/layout/BottomLink/BottomLink.tsx

@@ -15,12 +15,7 @@
  */
 
 import React from 'react';
-import {
-  ListItemIcon,
-  Divider,
-  Typography,
-  makeStyles,
-} from '@material-ui/core';
+import { Divider, Typography, makeStyles } from '@material-ui/core';
 import ArrowIcon from '@material-ui/icons/ArrowForward';
 import { BackstageTheme } from '@backstage/theme';
 import Box from '@material-ui/core/Box';

packages/core-components/src/layout/Sidebar/Items.tsx

@@ -204,7 +204,7 @@ export const SidebarItem = forwardRef<any, SidebarItemProps>((props, ref) => {
 
   if (isButtonItem(props)) {
     return (
-      <button aria-label={text ? text : props.to} {...childProps} ref={ref}>
+      <button aria-label={text} {...childProps} ref={ref}>
         {content}
       </button>
     );