This patch adds EthernetConfiguration class which represents a
static configuration and network capabilities of a configured ethernet
network interface.
EthernetConfiguration is used ONLY internally to store and track
ethernet configurations, and serves different functionality as
EthernetNetworkUpdateRequest.
Bug: 397536853
Test: atest ConnectivityCoverageTests
Flag: EXEMPT mainline
Change-Id: Ib175347096db25b9f2180a2e526746f1f3cf6ceb