`CompositionScopedBatch` does not support `IWeakReferenceSource`

### Describe the bug

This documented usage will cause a crash

### Why is this important?

Because we need `Completed` event with an auto revoker to work.

### Steps to reproduce the bug

```cpp
auto batch = compositor.CreateScopedBatch(winrt::Microsoft::UI::Composition::CompositionBatchTypes::Animation);
auto revoker = batch.Completed(winrt::auto_revoke, ...);
```

### Actual behavior

Crash

### Expected behavior

_No response_

### Screenshots

_No response_

### NuGet package version

WinUI 3 - Windows App SDK 1.8.3: 1.8.251106002

### Windows version

Windows 11 (24H2): Build 26100

### Additional context

_No response_

No source file or test is identified. Start by reproducing the documented C++ snippet with CompositionScopedBatch, IWeakReferenceSource, and the Completed auto revoker; done means the snippet no longer crashes and the Completed event works with an auto revoker.

Written by the indexing model from the issue text.