Add test coverage to ensure interop with Microsoft.Owin.Security and aspnetcore 3.0+ works

[natemcmaster]

In aspnet/Security#1916, we had to entirely disable Owin cookie interop tests as a result of changing target framework support. We should re-write these tests in a way that lets us test the supported scenarios without requiring a hack to run aspnetcore assemblies on .NET Framework.

The scenarios we need to ensure continue to work are:

• Cookies and keys created by ASP.NET Core 3.0+ interop with Owin/Katana using Microsoft.Owin.Security.Interop 2.1.
• Vice versa
• Any changes to cookie formats and key formats made in 3.0+ stay backwards compatible with DataProtection 2.1

[Eilon]

Closing because we don't have plans to continue supporting this scenario.