Create a fake async operation that returns a result immediately when invoked

AsyncOperationWrapper.cpp

```cpp
// Can be used in a similar way to .NET's Task.FromResult and PPL's concurrency::create_async (See https://github.com/microsoft/cppwinrt/issues/1036).
template <typename Result>
struct AsyncOperationWrapper : implements<AsyncOperationWrapper<Result>, Windows::Foundation::IAsyncOperation<Result>>
{
public:
    AsyncOperationWrapper(Result result) : m_Result(result) {}

    auto Id() const noexcept
    {
      return juv::as_value<juv::uint32>(this);
    }

    auto ErrorCode() const noexcept
    {
      return hresult(0);
    }

    auto Status() const noexcept
    {
      return Windows::Foundation::AsyncStatus::Completed;
    }

    auto Completed() const noexcept
    {
      return m_Completed;
    }

    void Completed(Windows::Foundation::AsyncOperationCompletedHandler<Result> const& value)
    {
      value(*this, Windows::Foundation::AsyncStatus::Completed);
      m_Completed = value;
    }

    auto GetResults() const noexcept
    {
      return m_Result;
    }

    void Cancel() const noexcept {}

    void Close() const noexcept {}
private:
    Result m_Result;
    Windows::Foundation::AsyncOperationCompletedHandler<Result> m_Completed;
};
```

Usage: ```cpp
IAsyncOperation<SomeType> operation = make<AsyncOperationWrapper<SomeType>>(SomeValue);
auto result = co_await operation;
// The value held by result should be equal to the original value you specified while constructing AsyncOperationWrapper<SomeType>.
```