Create a netlab graph from a subset of nodes

[ipspace]

The latter would probably garble any graph created by netlab (unless I missed the option to exclude node from a graph).

Originally posted by @a-v-popov in https://github.com/ipspace/netlab/discussions/2727

We can use the existing node-matching functionality available (for example) in netlab report, trim the nodes and links (or nodes and BGP neighbors) to the specified subset, and then create the graph.