Add highlight menu keys for all toggle pref controllers and custom slices

Bug: 204695404
Test: manual, robotest build pass, unit
Change-Id: Iad2e28ada8ddb766ffa7eff2c8dc581250cbd6f8

src/com/android/settings/gestures/GestureNavigationSettingsAssistController.java

@@ -19,6 +19,7 @@ package com.android.settings.gestures;
 import android.content.Context;
 import android.provider.Settings;
 
+import com.android.settings.R;
 import com.android.settings.core.TogglePreferenceController;
 
 /**
@@ -50,4 +51,9 @@ public class GestureNavigationSettingsAssistController extends TogglePreferenceC
         return SystemNavigationPreferenceController.isGestureAvailable(mContext) ? AVAILABLE
                 : UNSUPPORTED_ON_DEVICE;
     }
+
+    @Override
+    public int getSliceHighlightMenuRes() {
+        return R.string.menu_key_system;
+    }
 }