[Provider model] Add "Turn off/on Wi-Fi" link to Internet Panel

- Replace the left menu button with "Turn off/on Wi-Fi"
  - Remove the TurnOnWifiSlice

- Show "Wi-Fi is off" sub-title when Wi-Fi is disabled
  - Remove the "Wi\u-Fi is turned on" sub-title when APM is on.

Bug: 188710392
Test: manual test
atest -c InternetConnectivityPanelTest
make RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.panel

Change-Id: I53e200f6cadf8b712bf794bcbd5ff79f0f239cc0

src/com/android/settings/panel/PanelContent.java

@@ -20,6 +20,7 @@ import android.content.Intent;
 import android.net.Uri;
 
 import androidx.core.graphics.drawable.IconCompat;
+import androidx.fragment.app.FragmentActivity;
 
 import com.android.settingslib.core.instrumentation.Instrumentable;
 
@@ -94,8 +95,11 @@ public interface PanelContent extends Instrumentable {
 
     /**
      * Implement the click event for custom button.
+     *
+     * @param panelActivity the FragmentActivity from PanelFragment, the user can decide whether
+     * to finish activity or not.
      */
-    default void onClickCustomizedButton() {}
+    default void onClickCustomizedButton(FragmentActivity panelActivity) {}
 
     /**
      * Register to start receiving callbacks for custom button events.