Fix `Checkbox` default visual density to meet Material 3 guidelines (#159081)

Fixes [Compact Visual Density is wrongfully applied to Checkboxes with
`MaterialTapTargetSize.padded` on desktop platforms according to
Material 3 Guidelines](https://github.com/flutter/flutter/issues/156408)

### Description

This PR updates default `Checkbox` visual density to not depend on
`ThemeData.visualDenSity` as it will return `VisualDensity.compact` on
desktop and break Material 3 guidelines for `Checkbox`.

> [!NOTE]  
> This makes a similar fix as
https://github.com/flutter/flutter/pull/110722.

### 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,
      home: Scaffold(
        body: Center(
          child: Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              ColoredBox(
                color: Colors.amber,
                child: Checkbox(
                  materialTapTargetSize: MaterialTapTargetSize.padded,
                  value: true,
                  onChanged: (bool? value) {},
                ),
              ),
              Container(
                width: 48,
                height: 48,
                color: Colors.red,
                alignment: Alignment.center,
                child: const Text(
                  '48x48px',
                  style: TextStyle(fontSize: 10, color: Colors.white),
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}
```

</details>


<img width="577" alt="Screenshot 2024-11-18 at 18 02 01"
src="https://github.com/user-attachments/assets/d390c92f-dd62-4c42-b6b7-d4f101078618">



<img width="577" alt="Screenshot 2024-11-18 at 18 01 49"
src="https://github.com/user-attachments/assets/632e8d19-11bf-45c7-9be9-5c4fc308f3ea">


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we expect every widget to implement].
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- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

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