feat(graphql): add type-name-option-for-custom-type-naming

[mag123c]

PR Checklist

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Currently, when generating TypeScript definitions from GraphQL schema files, all type names are used as-is. This can lead to naming conflicts when you have similar type names across different domains (e.g., User database entity, User GraphQL type, UserDTO).

Issue Number: #3440

What is the new behavior?

Added a typeName option to DefinitionsGeneratorOptions that allows users to transform generated type names using a custom function.

Example usage:

definitionsFactory.generate({
  typePaths: ['./src/**/*.graphql'],
  path: './src/graphql.ts',
  typeName: (name) => `${name}Schema`
})

This will transform:

• User → UserSchema
• CreateUserInput → CreateUserInputSchema
• UserRole → UserRoleSchema

Root types (Query, Mutation, Subscription) remain unchanged as IQuery, IMutation, ISubscription.

Does this PR introduce a breaking change?

• Yes
• No

Other information

This is my first contribution to the NestJS GraphQL project. I've carefully studied the codebase and followed the existing patterns to implement this feature. Open to any feedback for improvements.