Add a new ErrorExtraInfo that the RemoteCommandRunner can use to store detailed error information in the case of RPC failure. Convert the RCR's error handling path to make use of this new EEI.

After this ticket, the runner should return a future that will be set with a single  ErrorCodes::RemoteCommandRunnerExecutionError error in the case of error. Any additional information about the underlying error (i.e. whether it was local or remote, write concern, etc) will be stored in the ErrorExtraInfo object.