scorer in AOSP Create WiFi scorer interface and score change callback interface in WifiManager; Define register and unregister methods for WiFi scorer. Test: atest android.net.wifi Bug: 135573686, 122133502, 136312816, 135572156 Change-Id: Ib51d877a463d1f69b31b9743917ea1b3590a30f7 Signed-off-by: Mingguang Xu <mingguangxu@google.com>