Add optional field to the benchmark

[DZakh]

I randomly checked the generated Typia code and noticed that strict parsing might become up ~5 times slower if you add an optional field. And I assume this is the same for other libraries, even if they are not precompiled. There might even be some bugs.

I think it's a pretty common field, so it'd be nice to add an optional field to the existing data object or an additional case.