Flutter json_serializable use `JsonValue` as the json key of Enum

### Which packages are impacted by your issue?

@graphql-codegen/flutter-freezed

### Describe the bug

The current version of [json_serializable](https://pub.dev/packages/json_serializable) uses `JsonValue` as the Enum json serialize key.

### Your Example Website or App

https://stackblitz.com/edit/github-mc3hpg?file=app_models.dart

### Steps to Reproduce the Bug or Issue

Schema.graphql

```
enum BookCategory {
BusinessCareer
Family
}
```
Generate

```
enum BookCategory {
@JsonKey(name: 'BusinessCareer')
businessCareer,
@JsonKey(name: 'Family')
family,
}
```

freezed generate
```

const _$BookCategoryEnumMap = {
BookCategory.businessCareer: 'businessCareer',
BookCategory.family: 'family',
}
```

freezed use `$enumDecode(_$BookCategoryEnumMap, e);` to trans from json.

got error
```
Invalid argument(s): `BusinessCareer` is not one of the supported values: businessCareer, family,

```

### Expected behavior

```
enum BookCategory {
@JsonValue('BusinessCareer')
businessCareer,
@JsonValue('Family')
family,
}
```

### Screenshots or Videos

_No response_

### Platform

```
"@graphql-codegen/cli": "5.0.2",
"@graphql-codegen/flutter-freezed": "^4.0.0",
"@graphql-codegen/introspection": "4.0.3",
"@graphql-codegen/typescript": "4.0.6",
"@graphql-codegen/typescript-resolvers": "4.0.6",
```

### Codegen Config File

_No response_

### Additional context

_No response_