[Dashboard] Fix unsaved changes badge React error (#154607)

## Summary

### Before

Since adding the tooltip to the unsaved changes badge in
#154253, React was throwing an
error to the console because the element in the top nav no longer had a
unique key:


https://user-images.githubusercontent.com/8698078/230927494-7cc931f8-68c6-4904-b99e-99b1b2872f94.mov

<br>


![image](https://user-images.githubusercontent.com/8698078/230925422-32f8ea9d-8c22-470e-a94e-0aa9eda0b4de.png)


### After

This PR fixes this by adding the key **to the tooltip** if the badge has
one; if it doesn't have a tooltip, then the key is added directly to the
`EuiBadge` as expected. It also ensures that the tooltip has the proper
a11y support (cc @elastic/kibana-accessibility) by adding the badge to
the tab order and using the <a
href="https://github.com/elastic/eui/blob/main/wiki/component-design.md#pass-through-props">pass-through-props</a>
to ensure that the tooltip shows up on focus:



https://user-images.githubusercontent.com/8698078/230929396-5a423c18-4a5f-410c-a3d3-9005022f8060.mov



### Checklist

- [x] Any UI touched in this PR is usable by keyboard only (learn more
about [keyboard accessibility](https://webaim.org/techniques/keyboard/))
- [x] Any UI touched in this PR does not create any new axe failures
(run axe in browser:
[FF](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/),
[Chrome](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd?hl=en-US))
- [x] This renders correctly on smaller devices using a responsive
layout. (You can test this [in your
browser](https://www.browserstack.com/guide/responsive-testing-on-local-server))
- [x] This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)



### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

src/plugins/navigation/public/top_nav_menu/top_nav_menu.tsx

@@ -82,12 +82,20 @@ export function TopNavMenu<QT extends AggregateQuery | Query = Query>(
   }
 
   function createBadge({ badgeText, toolTipProps, ...badgeProps }: Badge, i: number): ReactElement {
-    const badge = (
-      <EuiBadge key={`nav-menu-badge-${i}`} {...badgeProps}>
+    const Badge = ({ key, ...rest }: { key?: string }) => (
+      <EuiBadge key={key} tabIndex={0} {...rest} {...badgeProps}>
         {badgeText}
       </EuiBadge>
     );
-    return toolTipProps ? <EuiToolTip {...toolTipProps}>{badge}</EuiToolTip> : badge;
+
+    const key = `nav-menu-badge-${i}`;
+    return toolTipProps ? (
+      <EuiToolTip key={key} {...toolTipProps}>
+        <Badge />
+      </EuiToolTip>
+    ) : (
+      <Badge key={key} />
+    );
   }
 
   function renderBadges(): ReactElement | null {