Return data in Arrow format

[joshuataylor]

Have started tying this in using arrow2 as Rust NIF, which is what Polars uses and is a great library. Have a read through their documentation and guides, it's great.

I've started a conversation over on their discussions around how to return data, as I would like the rows listed in the same way. It probably doesn't need to return headers from the Rust NIF, and just columns.