Replace hidden NMS interface to network API

Replace the hidden NMS addInterfaceToNetwork and
removeInterfaceFromNetwork with calling INetd directly for
incoming ConnectivityService mainline.

Bug: 170598012
Test: atest FrameworksNetTests
Test: manually connect and disconnect network
Change-Id: I0f1f866be2f8084b992b340aeabfb5d62420686b