Changes to make eth service methods more testable am: a5f724dfdd am: 4f22cf4a85 am: bf585dba90

Original change: https://android-review.googlesource.com/c/platform/frameworks/opt/net/ethernet/+/1934759

Change-Id: I1d87ec14a50a4910d2a02eea210ca67cabcb8806
tree: 28e16901b342bb8c705e250ea82ada7e687d0dc8
  1. service-t/
  2. tests/