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Implement native str_putcsv

As title, here is the original [disscusion](https://old.reddit.com/r/PHP/comments/9fecs1/is_it_possible_to_add_the_str_putcsv_in_internal/) on Reddit. I think the `str_getcsv` is existed and the `str_putcsv` should be implemented. The PHP will support the `CSV` files/strings manipulation fully.