title: Superfluous 'runtimes' folder created in output directory for .NET 5 project
body: <p>I've just migrated a (WPF) .NET 4.6 project to .NET 5.</p>
  <p>I've noticed it is now creating a folder called 'runtimes' in the output directory with lots of platform-dependent dlls.</p>
  <p>Since this app will only run on Windows machines, is there anyway of preventing these folders being created during a build in Visual Studio?</p>