fixes [Chip border side color not working in Material3](https://github.com/flutter/flutter/issues/132922)

### 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(
      theme: ThemeData(
        useMaterial3: true,
        chipTheme: const ChipThemeData(
            // shape: RoundedRectangleBorder(
            //   side: BorderSide(color: Colors.amber),
            //   borderRadius: BorderRadius.all(Radius.circular(12)),
            // ),
            // side: BorderSide(color: Colors.red),
            ),
      ),
      home: const Example(),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(
        child: RawChip(
          shape: RoundedRectangleBorder(
            side: BorderSide(color: Colors.amber),
            borderRadius: BorderRadius.all(Radius.circular(12)),
          ),
          // side: BorderSide(color: Colors.red),
          label: Text('Chip'),
        ),
      ),
    );
  }
}

``` 

</details>

---

### Before

When `RawChip.shape` is provided with a `BorderSide`.

```dart
      body: Center(
        child: RawChip(
          shape: RoundedRectangleBorder(
            side: BorderSide(color: Colors.amber),
            borderRadius: BorderRadius.all(Radius.circular(12)),
          ),
          label: Text('Chip'),
        ),
      ),
```

![Screenshot 2023-08-24 at 17 54 54](https://github.com/flutter/flutter/assets/48603081/89e2c9b5-44c2-432e-97ff-8bb95b0d0fb1)

When `RawChip.shape` is provided with a `BorderSide` and also `RawChip.side` is provided. The  `RawChip.side` overrides the shape's side.

```dart
      body: Center(
        child: RawChip(
          shape: RoundedRectangleBorder(
            side: BorderSide(color: Colors.amber),
            borderRadius: BorderRadius.all(Radius.circular(12)),
          ),
          side: BorderSide(color: Colors.red),
          label: Text('Chip'),
        ),
      ),
```

![Screenshot 2023-08-24 at 17 55 37](https://github.com/flutter/flutter/assets/48603081/938803cc-d514-464b-b06b-e4841b9ad040)

---

### After

When `RawChip.shape` is provided with a `BorderSide`.

```dart
      body: Center(
        child: RawChip(
          shape: RoundedRectangleBorder(
            side: BorderSide(color: Colors.amber),
            borderRadius: BorderRadius.all(Radius.circular(12)),
          ),
          label: Text('Chip'),
        ),
      ),
```

![Screenshot 2023-08-24 at 17 51 29](https://github.com/flutter/flutter/assets/48603081/d6fcaaa9-8f5d-4180-ad14-062dd459ec45)

When `RawChip.shape` is provided with a `BorderSide` and also `RawChip.side` is provided. The  `RawChip.side` overrides the shape's side.

```dart
      body: Center(
        child: RawChip(
          shape: RoundedRectangleBorder(
            side: BorderSide(color: Colors.amber),
            borderRadius: BorderRadius.all(Radius.circular(12)),
          ),
          side: BorderSide(color: Colors.red),
          label: Text('Chip'),
        ),
      ),
```

![Screenshot 2023-08-24 at 17 52 31](https://github.com/flutter/flutter/assets/48603081/3fa46341-43f0-4fe7-a922-f1d8ba34028c)

---