Implement shared response types for GraphQL client generator

[devin-ai-integration]

📝 Description

This PR implements shared response types for the GraphQL client generator, extending the existing shared types mechanism (used for input types and enums) to also work for response types. This eliminates duplicate response classes when multiple queries/mutations use the same types.

Key Changes:

• Added responseClassToTypeSpecs map to track shared response types in GraphQLClientGeneratorContext
• Changed package structure from operation-specific packages (e.g., com.expediagroup.graphql.generated.myquery.Result) to shared packages (e.g., com.expediagroup.graphql.generated.types.Result)
• Removed nested response types from operation classes - they now reference shared types instead
• Extended sharedTypes mechanism to include response types alongside existing input types and enums
• Updated interface/union generation to work with the new shared package structure

Before:

// Multiple duplicate classes generated
import com.expediagroup.graphql.generated.query1.User
import com.expediagroup.graphql.generated.query2.User  // Duplicate!

After:

// Single shared class referenced by all operations
import com.expediagroup.graphql.generated.types.User

⚠️ Breaking Change Warning:
This PR changes the package structure of generated response types. Existing code that imports operation-specific response types will need to be updated to use the new shared package structure.

🧪 Test Status:
Integration tests are currently failing because they expect the old package structure and file count. The core implementation is working correctly (no runtime errors), but test expectations need to be updated to reflect the new behavior.

🔍 Critical Review Areas:

1. Package structure changes - Verify the new .types package approach is correct
2. Polymorphic type handling - Interface and union type generation logic has been modified significantly
3. Shared type deduplication - Ensure types with identical selection sets are properly shared
4. Backward compatibility impact - Assess migration requirements for existing users

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Link to Devin run: https://app.devin.ai/sessions/b480d92e3d824a38a59297e850f0e89e
Requested by: @akkp-windsurf

🔗 Related Issues

This addresses the requirement to modify the GraphQL client generator to create shared response types instead of operation-specific duplicate classes, extending the existing shared types pattern used for input types and enums.

[devin-ai-integration]

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