This property should helps users to implement custom retries logics.
Along with the property, the static function `Neo4jError.isRetriable(error)` and
the function `isRetriableError(error)` were added for saving boilerplates and avoid
the error typechecking to be spread accross the client and driver code base.
The internal function `canRetryOn(error)` and the `retry-strategy` file were removed
since the logic implemented there was moved to the `error` module replaced by
the `isRetriableError(error)` usage.