[Glitch] Fix intermediary responsive layout, accessibility on navigation in web UI

Port 0765324622 to glitch-soc

Co-authored-by: Yamagishi Kazutoshi <ykzts@desire.sh>
Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/components/avatar.js

@@ -70,6 +70,8 @@ export default class Avatar extends React.PureComponent {
         onMouseLeave={this.handleMouseLeave}
         style={style}
         data-avatar-of={account && `@${account.get('acct')}`}
+        role='img'
+        aria-label={account.get('acct')}
       />
     );
   }