fixes [NavigationRail can't have a transparent Hover color because there is always opacity set](https://github.com/flutter/flutter/issues/135866)

### 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 MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.green).copyWith(
          primary: Colors.transparent,
        ),
      ),
      home: const Example(),
    );
  }
}

class Example extends StatefulWidget {
  const Example({Key? key}) : super(key: key);

  @override
  State<StatefulWidget> createState() => _ExampleState();
}

class _ExampleState extends State<Example> {
  int _selectedIndex = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('NavigationRail Example'),
      ),
      body: Row(
        children: <Widget>[
          NavigationRail(
            selectedIndex: _selectedIndex,
            onDestinationSelected: (int index) {
              setState(() {
                _selectedIndex = index;
              });
            },
            labelType: NavigationRailLabelType.all,
            destinations: const <NavigationRailDestination>[
              NavigationRailDestination(
                icon: Icon(Icons.favorite_border),
                selectedIcon: Icon(Icons.favorite),
                label: Text('First'),
              ),
              NavigationRailDestination(
                icon: Icon(Icons.bookmark_border),
                selectedIcon: Icon(Icons.book),
                label: Text('Second'),
              ),
              NavigationRailDestination(
                icon: Icon(Icons.star_border),
                selectedIcon: Icon(Icons.star),
                label: Text('Third'),
              ),
            ],
          ),
          const VerticalDivider(thickness: 1, width: 1),
          Expanded(
            child: Center(
              child: Text('Selected Index: $_selectedIndex'),
            ),
          )
        ],
      ),
    );
  }
}
```

</details>