Fix nodes_within_range

[blegat]

Fixes a few issues:

• network is not defined
• collect gives you a Vector{Int} which has two issues:
  • It is not a subtype of AbstractSet{Int}, we could change the signature
  • Since we just want to iterate once over it, it's a waste to collect
• If node_list is an AbstractSet, we should collect in case range is Inf since in the other case, it returns a vector