Show icons for allowed sounds

(Some icons are temporary, until we get the final assets)

Also some fixes/improvements to CircularIconsPreference:
* Show the correct placeholder and +N icons.
* Fix the displayIcons-before-measure case (global layout listener was incorrect).
* Properly cancel pending image load futures (field didn't point to the actual future).
* Don't reload icons if it's the same set (depends on equals() for the items, so unfortunately doesn't work for AppEntry yet).

Test: atest com.android.settings.notification.modes
Bug: 346551087
Flag: android.app.modes_ui
Change-Id: I9d029a5fdd785ada4e2ba4d8a90eba72b5fb9085

src/com/android/settings/notification/modes/CircularIconSet.java

@@ -22,6 +22,7 @@ import android.graphics.drawable.Drawable;
 
 import androidx.annotation.VisibleForTesting;
 
+import com.google.common.base.MoreObjects;
 import com.google.common.collect.ImmutableList;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ListeningExecutorService;
@@ -61,6 +62,15 @@ class CircularIconSet<T> {
         mCachedIcons = new ConcurrentHashMap<>();
     }
 
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this).add("items", mItems).toString();
+    }
+
+    boolean hasSameItemsAs(CircularIconSet<?> other) {
+        return other != null && this.mItems.equals(other.mItems);
+    }
+
     int size() {
         return mItems.size();
     }