skip test_rsn_platform_driver: it is very basic and would need adjustments as we work on various changes; general functionality is more comprehensively covered by other tests.
introduce method _get_network_definition as a minor refactor in base class for platform tests to facilitate setting the network definition more directly from other sources (not necessarily the OMS interface)
clean-up in network_util.py, in particular to prepare deserialize_network_definition(ser) for more general use in integration tests.  (also removed unneeded create_node_network(network_map))
use direct yml for network definition in integration tests; at the moment only in test_mission_manager, but eventually in other tests as well (this is part of the clean-up and additions related with port-instr associations)
Merge pull request #2125 from carueda/pa_port-intr-assocs

M101: adjustments, clean-up, re port-intrument associations