Implement Wi-Fi QR code scanner flow.

1. Implements WifiNetworkConfig Wi-Fi connection method
2. Shows error message when the QR code is not valid and hides it after 2s
3. In configurator mode, launchs AddDeviceFragment for a valid QR code
4. In enrollee mode, connects Wi-Fi for a valid QR code

Bug: 118794978
Test: manual test
      atest WifiQrCodetest
      atest WifiDppConfiguratorActivityTest
      atest WifiDppEnrolleeActivityTest
      atest WifiDppQrCodeScannerFragmentTest

Change-Id: Ie4731b22df295c60906156d33ea28dad9c084ce4

tests/robotests/src/com/android/settings/wifi/qrcode/QrCameraTest.java

@@ -85,6 +85,11 @@ public class QrCameraTest {
         public void setTransform(Matrix transform) {
             // Do nothing
         }
+
+        @Override
+        public boolean isValid(String qrCode) {
+            return true;
+        }
     }
 
     private ScannerTestCallback mScannerCallback;