Always pass back a managed IDataObject if we can get the original

[JeremyKuhne]

The unfortunate caveat of returning the original object is that the behavior of calling through the OLE IDataObject proxy results in different behavior than calling through the original object. This primarily happens for autoConvert scenarios, where no such concept exists in the COM interfaces. As such, when calling through the COM interface, autoConvert is always considered to be true.

To mitigate the COM caveat, we do not give back the original DataObject if we created it implicitly via
Clipboard.SetData. This allows the calls to go through the proxy, which gets the expected autoConvert` behavior.

Doing this should avoid BinaryFormatter scenarios when OLE actions are made in process without copy set to true.