Update Network & internet->Wi-Fi to use MasterSwitchPreference.

- Add a preference controller for Network & internet->Wi-Fi to control
  the preference toggling and summary update.
- Refactor WifiSettings and WifiEnabler to share code between the new
  wifi preference controller and the wifi setting.
- Refactor BluetoothSummaryHelper to have a common base class with the
  WifiSummaryHelper.
- Rename the summary helper to summary updater.

Bug: 34280769
Test: make RunSettingsRoboTests
Change-Id: I00ebfc161bcef89331bb41ba405ed8cb8232d248

src/com/android/settings/connecteddevice/ConnectedDeviceDashboardFragment.java

@@ -39,7 +39,6 @@ public class ConnectedDeviceDashboardFragment extends DashboardFragment {
 
     private static final String TAG = "ConnectedDeviceFrag";
     private UsbModePreferenceController mUsbPrefController;
-    private BluetoothMasterSwitchPreferenceController mBluetoothPreferenceController;
 
     @Override
     public int getMetricsCategory() {
@@ -67,10 +66,11 @@ public class ConnectedDeviceDashboardFragment extends DashboardFragment {
         mUsbPrefController = new UsbModePreferenceController(context, new UsbBackend(context));
         lifecycle.addObserver(mUsbPrefController);
         controllers.add(mUsbPrefController);
-        mBluetoothPreferenceController = new BluetoothMasterSwitchPreferenceController(
+        final BluetoothMasterSwitchPreferenceController bluetoothPreferenceController =
+            new BluetoothMasterSwitchPreferenceController(
                 context, Utils.getLocalBtManager(context));
-        lifecycle.addObserver(mBluetoothPreferenceController);
-        controllers.add(mBluetoothPreferenceController);
+        lifecycle.addObserver(bluetoothPreferenceController);
+        controllers.add(bluetoothPreferenceController);
         return controllers;
     }