[REQ] [Go] Improved error message when model implements RFC7807

[gcatanese]

Is your feature request related to a problem? Please describe.

When the API call returns an error (3xx, 4xx, 5xx) the generated Go client returns the GenericOpenAPIError with body, error and model of the returned errors. The error attribute includes the HTTP Status Code (ie 422).

Describe the solution you'd like

When the problem error JSON implements RFC7807 it would be much better to include Title and Detail so that the underlying cause of the error is immediately visible.

Describe alternatives you've considered

When logging the error only the status code is available. At the moment the client application needs to parse/decode the full HTTP response to have a better understanding of the cause of the error.