[Federation] Add FederationInterceptor#allow-partial-result config.

When we use Federation, we will have multiple sub-clusters, and some interfaces need to call all clusters to get results, 
such as getNodes, getNodeToLabels, etc.

But if the sub-cluster is unavailable when we call the interface, should the interface return the result?

The current code is to return the result.If the result is returned, the result information is inaccurate; 
if the result is not returned, it is not user-friendly

We'd better add a parameter control, the user chooses whether to report an error or return the result.