Reset count to 0 when re-queueing control.

When a layout of a control exceeds the maximum passes and we re-queue it, reset the attempt count to 0 because otherwise it can end up stuck in the layout queue forever even when the next layout can succeed with e.g. 2 passes. This can happen with `ItemsRepeater`.

src/Avalonia.Layout/LayoutQueue.cs

@@ -77,7 +77,7 @@ namespace Avalonia.Layout
             {
                 if (_shouldEnqueue(item.Key))
                 {
-                    _loopQueueInfo[item.Key] = new Info() { Active = true, Count = item.Value.Count + 1 };
+                    _loopQueueInfo[item.Key] = new Info() { Active = true, Count = 0 };
                     _inner.Enqueue(item.Key);
                 }
             }