Wifi: add throughputPredictor and throughputScorer classes

They are used in WifiNetworkSelector for predict throughput and
calculate network selection score with Nss, Rssi, channelWidth,
wifiStandard and channelUtilization info collected from scan and
bluetoothConnected information from BluetoothAdaptor broadcast message.

Bug: 141770991
Test: Wifi unit test with frameworks/opt/net/wifi/tests/wifitests/runtests.sh
Test: run manual test to make sure throughput and score are calculated
      correctly with various APs with 2, 4 and 8 antennas in 20, 40 and 80MHz
      modes with and without BT connected.

Change-Id: I1ae36460d2f719cce157d94f5b65039597878f49
16 files changed