Restore C# goto label targets

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: owen-mc

csharp/ql/lib/semmle/code/csharp/controlflow/internal/ControlFlowGraph.qll

@@ -162,11 +162,7 @@ module Ast implements AstSig<Location> {
 
   class Stmt = CS::Stmt;
 
-  class LabeledStmt extends Stmt {
-    LabeledStmt() { none() }
-
-    Stmt getStmt() { none() }
-  }
+  class LabeledStmt = CS::LabelStmt;
 
   class Expr = CS::Expr;