When an iface goes inactive, xt_qtaguid maintains historical counters instead of discarding. Now reading and returning those values in NetworkManagementService summary calls. Tests to verify stats are returned. Modify NetworkStats to include rxPackets and txPackets values, and move to Entry to eventually hide internal storage details. Bug: 4984539 Change-Id: I1ba0bb5580c62e946d9dff2cc2a6f64aff403efc