This removes the dependency on Microsoft.WindowsDesktop.App.Ref, which
is tied to the runtime version. We can't trivially add it to the
standard list of sdk packages, because its version doesn't exactly match
either the runtime or sdk versions. For example: 9.0.0-preview.1.24081.3
is needed for runtime 9.0.0-preview.1.24081.5.
Since we don't currently support windows targets, we'll just disable
this for now.
This will allow the sdks to be updated without changing the deps file.
