Merge changes Ie1a91959,Ic189b2c0,I39d70e0a,Ibb5f1402

* changes:
  TestNetworkInterface: add support for MacAddress and MTU
  TestNetworkService: add support for creating iface without carrier
  TestNetworkService: Add support for toggling carrier on tun/tap
  TestNetworkService: Fix TestNetworkInterface parcel flags