Fix file-scoped namespace collection on net8.0

Restore unconditional FileScopedNamespaceDeclarationSyntax handling; the vs-extension ROSLYN_4_0_OR_GREATER guard is undefined on master.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: floriankraemer

CognitiveCodeAnalysis/src/CognitiveAnalysis/CognitiveCodeAnalyser.cs

@@ -368,7 +368,6 @@ private static IEnumerable<string> CollectNestedClasses(ClassDeclarationSyntax c
     // Collect namespace parts (including file-scoped namespaces)
     private static IEnumerable<string> CollectNamespaceParts(ClassDeclarationSyntax classNode)
     {
-#if ROSLYN_4_0_OR_GREATER
         return classNode.Ancestors()
             .OfType<NamespaceDeclarationSyntax>()
             .Select(n => n.Name.ToString())
@@ -377,12 +376,6 @@ private static IEnumerable<string> CollectNamespaceParts(ClassDeclarationSyntax
                 .Select(ns => ns.Name.ToString())
             )
             .Reverse();
-#else
-        return classNode.Ancestors()
-            .OfType<NamespaceDeclarationSyntax>()
-            .Select(n => n.Name.ToString())
-            .Reverse();
-#endif
     }
 
     private static int CalculateNestingLevels(MethodDeclarationSyntax methodNode, CognitiveConfiguration configuration)