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/accessibility/MagnificationGesturesPreferenceController.java

@@ -76,6 +76,11 @@ public class MagnificationGesturesPreferenceController extends TogglePreferenceC
         return true;
     }
 
+    @Override
+    public int getSliceHighlightMenuRes() {
+        return R.string.menu_key_accessibility;
+    }
+
     @Override
     public CharSequence getSummary() {
         int resId = 0;