Mark side-effecting iterator dereference as a good case

Treat the unused range-for variable as intentionally unreported because its initializer may have side effects.

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

Author: jketema

cpp/ql/test/query-tests/Best Practices/Unused Entities/UnusedLocals/code2.cpp

@@ -105,7 +105,7 @@ void test_range_based_for()
 		output(v1);
 	}
 
-	for (int v2 : myContainer) // $ MISSING: Alert // BAD: v2 is not used (iterator dereference may have side effects)
+	for (int v2 : myContainer) // GOOD: iterator dereference may have side effects
 	{
 	}
 }