Add ability to customize `NavigationBar` indicator overlay and fix indicator shape for the overlay (#138901)

fixes [Provide ability to override `NavigationBar` indicator ink response overlay](https://github.com/flutter/flutter/issues/138850)
fixes [`NavigationBar.indicatorShape` is ignored, `NavigationBarThemeData.indicatorShape` is applied to the indicator inkwell](https://github.com/flutter/flutter/issues/138900)

### Code sample

<details>
<summary>expand to view the code sample</summary> 

```dart
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        bottomNavigationBar: NavigationBarExample(),
      ),
    );
  }
}

class NavigationBarExample extends StatefulWidget {
  const NavigationBarExample({super.key});

  @override
  State<NavigationBarExample> createState() => _NavigationBarExampleState();
}

class _NavigationBarExampleState extends State<NavigationBarExample> {
  int index = 0;

  @override
  Widget build(BuildContext context) {
    return NavigationBar(
      elevation: 0,
      overlayColor: const MaterialStatePropertyAll<Color>(Colors.transparent),
      // indicatorShape: RoundedRectangleBorder(
      //   borderRadius: BorderRadius.circular(4.0),
      // ),
      indicatorColor: Colors.transparent,
      selectedIndex: index,
      onDestinationSelected: (int index) {
        setState(() {
          this.index = index;
        });
      },
      destinations: const <Widget>[
        NavigationDestination(
          selectedIcon: Icon(Icons.home_filled),
          icon: Icon(Icons.home_outlined),
          label: 'Home',
        ),
        NavigationDestination(
          selectedIcon: Icon(Icons.favorite),
          icon: Icon(Icons.favorite_outline),
          label: 'Favorites',
        ),
      ],
    );
  }
}

```

</details>

### Before

#### Cannot override `NavigationBar` Indicator ink well overlay

![Screenshot 2023-11-22 at 18 22 48](https://github.com/flutter/flutter/assets/48603081/06f54335-71ee-4882-afb0-53b614933c38)

#### Indicator shape is ignored for the indicator overlay

![Screenshot 2023-11-22 at 15 29 52](https://github.com/flutter/flutter/assets/48603081/913e0f77-48f4-4c6e-87f3-52c81b78f3d9)

### After

#### Can use `NavigationBar.overlayColor` or `NavigationBarThemeData.NavigationBar` to override default indicator overlay

`overlayColor: MaterialStatePropertyAll<Color>(Colors.red.withOpacity(0.33)),`

![Screenshot 2023-11-22 at 18 22 08](https://github.com/flutter/flutter/assets/48603081/28badae4-a7c7-4bf0-8bcc-278a1f84729d)

`overlayColor: MaterialStatePropertyAll<Color>(Colors.transparent),`

![Screenshot 2023-11-22 at 18 22 25](https://github.com/flutter/flutter/assets/48603081/674b48b1-f66a-4d91-9f10-ad307416ac32)

#### Indicator shape is respected for the indicator overlay

![Screenshot 2023-11-22 at 15 30 36](https://github.com/flutter/flutter/assets/48603081/ae9a3627-787e-45ac-9319-2ea8ea1e6ae6)