API changes to support Throttle/Metering

For transaction support query use gocbcore. We need APIs from gocbcore so that we can pass information from "@cbq-engine" user to KV so that KV will not throttle the request. Also as...

As part of payload from KV all RCU/WCU need to be aggregated including atr management which will be returned as part of each request (Insert,Get,Replace, Delete, Commit,Rollback etc).