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

src/com/android/settings/wifi/dpp/WifiDppQrCodeBaseFragment.java

@@ -101,6 +101,13 @@ public abstract class WifiDppQrCodeBaseFragment extends InstrumentedFragment {
         mDescription.setText(description);
     }
 
+    /** optional, for WifiDppQrCodeScannerFragment */
+    protected void showErrorMessage(boolean show) {
+        if (mErrorMessage != null) {
+            mErrorMessage.setVisibility(show ? View.VISIBLE : View.INVISIBLE);
+        }
+    }
+
     /** optional, for WifiDppQrCodeScannerFragment */
     protected void setErrorMessage(String errorMessage) {
         if (mErrorMessage != null) {