Revise layout for Wifi Setup in XLarge screen

- revise xml for new layout
- introduce padding View objects for resizing screen when
  software keyboard is shown.
- We now don't show the detailed status of Wi-Fi module anymore
  in SetupWizard flow (like "disconnected", "connecting", etc.)
- remove Forget button and relevant code.

Bug: 3347865
Change-Id: Ieab3246f06ee73af59e247b3f9f31c7570efc71f

src/com/android/settings/wifi/WifiSettings.java

@@ -567,7 +567,7 @@ public class WifiSettings extends SettingsPreferenceFragment
     public void onClick(DialogInterface dialogInterface, int button) {
         if (mInXlSetupWizard) {
             if (button == WifiDialog.BUTTON_FORGET && mSelectedAccessPoint != null) {
-                ((WifiSettingsForSetupWizardXL)getActivity()).onForgetButtonPressed();
+                forget();
             } else if (button == WifiDialog.BUTTON_SUBMIT) {
                 ((WifiSettingsForSetupWizardXL)getActivity()).onConnectButtonPressed();
             }