make elements under image explorer view tab keyboard accessible (#2422)

libs/interpret-vision/src/lib/VisionExplanationDashboard/Controls/ImageList.tsx

@@ -79,6 +79,7 @@ export class ImageList extends React.Component<
           className={classNames.list}
           getPageHeight={this.getPageHeight}
           getItemCountForPage={this.getItemCountForPage}
+          tabIndex={0}
         />
       </FocusZone>
     );