Update Get Full Order Book API to v3 that requires authentication

[denistorresan]

The method RestClient.orderBookAPI().getFullLevel2OrderBook returns a 404 not found because the API Get Full Order Book(aggregated) was updated to V3 and now also requires authentication as described here:

https://docs.kucoin.com/#get-part-order-book-aggregated

I fixed updating the orderBookAPI and now extends AuthRetrofitAPIImpl.