anchor.diff:  `IApiCallDetails.Success` and `ResponseBase.IsValid` have been simplified, making it easier to inspect 
   if a request to Elasticsearch was indeed successful or not.
   
  +[float]
   ==== Low Level Client
   
   If the status code from Elasticsearch is `2xx` then `.Success` will be `true`. In instances where a `404` 
  
positive.code: 
  This is controlled via `IConnectionConfiguration.StatusCodeToResponseSuccess`, which currently has no public setter.
  
  ==== High Level Client
  
  The NEST high level client overrides `StatusCodeToResponseSuccess`, whereby `404` status codes now sets `.Success` as `true`.
  
negative.code: 
  In instances where methods can benefit from returning an interface, these have been left intact, for example, `ISearchResponse<T>`.
  
  [float]
  ==== Why make the change? 
  
  Firstly, this significantly reduces the number of types in 
  