Notargets overriding GetFrameworkPaths causes warnings

[vikukush]

After a recent change in NoTarget SDK, GetFrameworkPaths has become stubbed. This causes warnings to appear if any .NET PackageReference is used, because ResolvePackageAssets will pick up and emit standard Framework dependencies as FrameworkAssemblies and feed them into ResolveAssemblyReference, which will be unable to resolve those standard references, because .NET framework SDK path is no longer set