Implement Wi-Fi DPP flow

1. Wi-Fi DPP hanshake fail UI
2. Show Wi-Fi DPP QR code information field on WifiDppAddDeviceFragment if it's available.
3. Click 'Choose Different Network' button will show WifiDppChooseSavedWifiNetworkFragment
4. After QR code scanner scans success, WifiDppConfiguratorActivity caches WifiQrCode instead
   of just a QR code string

Bug: 122429170
Test: manual test
Change-Id: I1ce1b014ff86903b5a7a8f3575cc98eb1079583c

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

@@ -20,7 +20,6 @@ import android.content.Intent;
 import android.net.wifi.WifiConfiguration;
 import android.text.TextUtils;
 
-import androidx.annotation.Keep;
 import androidx.annotation.VisibleForTesting;
 
 import java.util.Arrays;
@@ -49,7 +48,6 @@ import java.util.regex.Pattern;
  * H         true       Optional. True if the network SSID is hidden.
  *
  */
-@Keep
 public class WifiQrCode {
     public static final String SCHEME_DPP = "DPP";
     public static final String SCHEME_ZXING_WIFI_NETWORK_CONFIG = "WIFI";
@@ -86,7 +84,6 @@ public class WifiQrCode {
     // Data from parsed ZXing reader library's Wi-Fi Network config format
     private WifiNetworkConfig mWifiNetworkConfig;
 
-    @Keep
     public WifiQrCode(String qrCode) throws IllegalArgumentException {
         if (TextUtils.isEmpty(qrCode)) {
             throw new IllegalArgumentException("Empty QR code");
@@ -172,7 +169,6 @@ public class WifiQrCode {
         return null;
     }
 
-    @Keep
     @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
     protected String removeBackSlash(String input) {
         if (input == null) {
@@ -199,7 +195,6 @@ public class WifiQrCode {
         return sb.toString();
     }
 
-    @Keep
     public String getQrCode() {
         return mQrCode;
     }
@@ -210,25 +205,22 @@ public class WifiQrCode {
      * SCHEME_DPP for standard Wi-Fi device provision protocol; SCHEME_ZXING_WIFI_NETWORK_CONFIG
      * for ZXing reader library' Wi-Fi Network config format
      */
-    @Keep
     public String getScheme() {
         return mScheme;
     }
 
     /** Available when {@code getScheme()} returns SCHEME_DPP */
-    @Keep
-    public String getPublicKey() {
+     @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
+    protected String getPublicKey() {
         return mPublicKey;
     }
 
     /** May be available when {@code getScheme()} returns SCHEME_DPP */
-    @Keep
     public String getInformation() {
         return mInformation;
     }
 
     /** Available when {@code getScheme()} returns SCHEME_ZXING_WIFI_NETWORK_CONFIG */
-    @Keep
     public WifiNetworkConfig getWifiNetworkConfig() {
         if (mWifiNetworkConfig == null) {
             return null;