C#: Use stubs for the CWE-838 testcase

Author: michaelnebel

csharp/ql/test/query-tests/Security Features/CWE-838/options

@@ -1 +1,4 @@
-semmle-extractor-options: ${testdir}/../../../resources/stubs/System.Web.cs ${testdir}/../../../resources/stubs/System.Windows.cs /r:System.Collections.Specialized.dll ${testdir}/../../../resources/stubs/System.Net.cs /r:System.ComponentModel.Primitives.dll /r:System.ComponentModel.TypeConverter.dll ${testdir}/../../../resources/stubs/System.Data.cs /r:System.Data.Common.dll
+semmle-extractor-options: /nostdlib /noconfig
+semmle-extractor-options: --load-sources-from-project:${testdir}/../../../resources/stubs/_frameworks/Microsoft.NETCore.App/Microsoft.NETCore.App.csproj
+semmle-extractor-options: --load-sources-from-project:${testdir}/../../../resources/stubs/System.Data.SqlClient/4.8.3/System.Data.SqlClient.csproj
+semmle-extractor-options: ${testdir}/../../../resources/stubs/System.Web.cs ${testdir}/../../../resources/stubs/System.Windows.cs