Create a main switch preference widget.

Based on our ux spec, we create this widget to
let everyone can follow up our spec easily.

Bug: 175181773
Test: Run robotest and apply this widget in Settings and see the ui
Change-Id: I4ea5f38c44aacfeb2c8dbe4a7d31159712f95441
diff --git a/packages/SettingsLib/Android.bp b/packages/SettingsLib/Android.bp
index 23cb36f..3834162 100644
--- a/packages/SettingsLib/Android.bp
+++ b/packages/SettingsLib/Android.bp
@@ -43,6 +43,7 @@
         "SettingsLibSearchWidget",
         "SettingsLibSettingsSpinner",
         "SettingsLibLayoutPreference",
+        "SettingsLibMainSwitchPreference",
         "SettingsLibActionButtonsPreference",
         "SettingsLibEntityHeaderWidgets",
         "SettingsLibBarChartPreference",