Support fetching node details through node label/rank instead of ID

[fbarl]

If we could call /api/topology/{name}/{id} with node labels instead of IDs, we would be able to load node details directly if only node labels were provided in the URL.

As far as I can see, this is the only backend blocker for resolving #2030 and it would only require us to do a bit more sophisticated search through nodes in handleNode in api_topology.go.

cc @rade @dlespiau

[rade]

What exactly do you mean by "node labels"? The label field in the json? For k8s that does contain the k8s name, but don't we also need the namespace? Note that the rank field combines namespace and name.

[fbarl]

What exactly do you mean by "node labels"? The label field in the json?

Yeah, I did mean the label field originally, but it makes more sense to include namespace in the name. I guess rank is exactly what we want since for controllers it has the same format as our Deploy/Monitor workload IDs, it's just the name rank that I find confusing :P