Provide a new API to enable or disable ethernet. Also have a listener for call to check whether enable state is sucessful. Bug: 171872016 Test: atest EthernetServiceTests Change-Id: Iee4b48511ff668a2a7df90fd9bfe563d7ff23940 Merged-In: Iee4b48511ff668a2a7df90fd9bfe563d7ff23940