The overloads of async_rpc::sendCommand and async_rpc::sendHedgedCommand that accept an OperationContext should also optionally accept a baton, in addition to a TaskExecutor. When a baton is provided, it should be used to run continuations that the rpc layer schedules before and after sending a command to the network via TaskExecutor::scheduleRemoteCommand. It should additionally be passed to the lower networking layers so that it can be used for polling if it is a NetworkingBaton.