Define menu keys for highlighting the menu entry on 2-pane UI

- Define an attribute for highlightable menu keys
- List the keys for Settings menu entries
- Support parsing the attribute

Bug: 199017944
Test: robotest
Change-Id: I5759bff591c79d498fffb8b2c2b57f2cb66c4421

src/com/android/settings/widget/HighlightablePreferenceGroupAdapter.java

@@ -105,7 +105,7 @@ public class HighlightablePreferenceGroupAdapter extends PreferenceGroupAdapter
         context.getTheme().resolveAttribute(android.R.attr.selectableItemBackground,
                 outValue, true /* resolveRefs */);
         mNormalBackgroundRes = outValue.resourceId;
-        mHighlightColor = context.getColor(R.color.preference_highligh_color);
+        mHighlightColor = context.getColor(R.color.preference_highlight_color);
     }
 
     @Override