Transmitting multiple default networks to netd

Updating ConnectivityService to transmit network information to netd as
part of supporting multiple default networks.

Bug: 176191930
Bug: 172347841
Test: atest FrameworksNetTests
atest NetworkStackTests
atest FrameworksNetIntegrationTests
atest NetworkStackIntegrationTests
atest CtsNetTestCasesLatestSdk

Change-Id: I5851a36e3c3ccb45f4cb3ff85e0fc1352f64dc70