Revise Neiborhood finder to allow searching for specific Taxon

[gloriachin]

It would be nice to add another parameter of taxon="xxx" in the Neiborhood_finder function to specify the returned genes only in certain Species. Such as only return human genes, or mouse genes.

The current function is used like this:
input_node_id, result, result_parsed, result_ranked_by_primary_infores = TCT.Neiborhood_finder('NCBIGene:596', node2_categories = ['biolink:Gene', 'biolink:Protein'], APInames = select_APIs, metaKG = selected_metaKG, API_predicates = API_predicates)