Statsd: Formalize WifiManager#requestActivityInfo

Rename WifiManager#requestActivityInfo to
getWifiActivityEnergyInfoAsync and convert
ResultReceiver to a formal listener interface.

Bug: 145244073
Test: m -j statsd_test && adb root && adb sync data && adb shell data/nativetest64/statsd_test/statsd_test
Test: atest CtsStatsdHostTestCases
Change-Id: I3e5b6f18f18b487683863934c3d0cba7be07a778