Improve the errors around UseStartup/Configure - Today we throw a...

Improve the errors around UseStartup/Configure - Today we throw a NotSupportedException when you try to call any of the methods that register callbacks for wiring up the ASP.NET Core pipeline. Unfortunately, this conflicts with another NotSupportedException that doesn't make much sense. We fix this by delegating to ISupportsStartup before attempting to set the application name. - Improved the existing test (#36060)

Co-authored-by: David Fowler <davidfowl@gmail.com>