fix(react, vue): add default value for navManager on tabs (#29865)

Issue number: N/A

---------

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## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

React: Refreshes the app upon a tab button press and returns to the
first tab content.
Vue: Does not render the tabs when the app doesn't use a router at all
because of `ionRouter` not being defined.

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- React: Users can press on the tab button without having the app
refresh and displays the associated tab content.
- Vue: Renders the tabs when router is not present.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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  2. Update the BREAKING.md file with the breaking change.
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## Other information

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screenshots of how the component looks before and after the change. -->

Dev build: 8.3.1-dev.11726094383.1cdbab6f

How to test:
I recommend using the playgrounds in the Ionic Framework docs repo since
those playgrounds are setup to not have any routers at a high level.

1. Navigate to the [basic usage
section](https://ionic-docs-git-rou-11138-ionic1.vercel.app/docs/api/tabs#basic-usage)
2. Select React
3. Open the StackBlitz example
4. Click on any tab button
5. Notice that the app refreshes and returns to the first tab content
6. Install the dev build: `npm install
@ionic/react@8.3.1-dev.11726094383.1cdbab6f`
7. Verify that the app doesn't refresh and reset the content after
clicking on any tab button
8. Navigate to the [basic usage
section](https://ionic-docs-git-rou-11138-ionic1.vercel.app/docs/api/tabs#basic-usage)
9. Select Vue
10. Open the StackBlitz example
11. Notice that tabs doesn't render
12. Open the console and notice that there's an error `ionRouter is
undefined`
13. Install the dev build: `npm install
@ionic/vue@8.3.1-dev.11726094383.1cdbab6f`
14. Verify that it renders
15. Verify that the console no longer shows the error

packages/react/src/components/navigation/IonTabBar.tsx

@@ -212,8 +212,10 @@ class IonTabBarUnwrapped extends React.PureComponent<InternalProps, IonTabBarSta
       if (this.props.onIonTabsDidChange) {
         this.props.onIonTabsDidChange(new CustomEvent('ionTabDidChange', { detail: { tab: e.detail.tab } }));
       }
-      this.setActiveTabOnContext(e.detail.tab);
-      this.context.changeTab(e.detail.tab, currentHref, e.detail.routeOptions);
+      if (this.props.routerOutletRef?.current) {
+        this.setActiveTabOnContext(e.detail.tab);
+        this.context.changeTab(e.detail.tab, currentHref, e.detail.routeOptions);
+      }
     }
   }