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/core/gateway/SettingsGateway.java

@@ -294,7 +294,6 @@ public class SettingsGateway {
             "com.android.settings.ManageApplicationsDashboardAlias",
             "com.android.settings.PaymentSettingsDashboardAlias",
             // Home page > Network & Internet
-            "com.android.settings.WifiDashboardAlias",
             "com.android.settings.DataUsageDashboardAlias",
             // Home page > Security
             "com.android.settings.LocationDashboardAlias",