C#: Base tests for CWE-539 on stubs.

Author: michaelnebel

csharp/ql/test/query-tests/Security Features/CWE-539/PersistentCookie/options

@@ -1 +1,3 @@
-semmle-extractor-options: ${testdir}/../../../../resources/stubs/System.Web.cs /r:System.Collections.Specialized.dll
+semmle-extractor-options: /nostdlib /noconfig
+semmle-extractor-options: --load-sources-from-project:${testdir}/../../../../resources/stubs/_frameworks/Microsoft.NETCore.App/Microsoft.NETCore.App.csproj
+semmle-extractor-options: ${testdir}/../../../../resources/stubs/System.Web.cs