feat: modify model-state error responses to conform to API standards

[Ace2489]

Description

This PR addresses the issue of the errors generated by ASP.NET's model-state validation not aligning with the recommended standard for all HNG boilerplate backends.

Changes proposed

What were you told to do?

Modify the error responses generated by the model-state validation to conform with the standards for all HNG Boilerplate backends.

What did you do?

• Created custom error objects.
• Created a custom model-state response factory.
• Configured the response factory to override the default factory for validation errors.

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