Revise homepage colors

- Increase the contrast ratio of the search bar
- Adjust the color of IA icons

Test: visual
Fixes: 179632631
Change-Id: I9b4fc4d671183929d4b2fed27cba8600d56cc74c

src/com/android/settings/Utils.java

@@ -1220,7 +1220,7 @@ public final class Utils extends com.android.settingslib.Utils {
      */
     @ColorInt
     public static int getHomepageIconColor(Context context) {
-        return getColorAttrDefaultColor(context, android.R.attr.textColorPrimary);
+        return getColorAttrDefaultColor(context, android.R.attr.textColorSecondary);
     }
 
     public static boolean isProviderModelEnabled(Context context) {