C++: Support C++20 range-based for initializers

cpp/ql/lib/semmlecode.cpp.dbscheme

@@ -2050,8 +2050,11 @@ switch_body(
     int body_id: @stmt ref
 );
 
+@stmt_for_or_range_based_for = @stmt_for
+                             | @stmt_range_based_for;
+
 for_initialization(
-    unique int for_stmt: @stmt_for ref,
+    unique int for_stmt: @stmt_for_or_range_based_for ref,
     int init_id: @stmt ref
 );