Instantiate DuckDBClient for Arrow tables

[libbey-observable]

Works with #8953 in observablehq

This is a small change to instantiate a DuckDBClient for Arrow tables, but it comes with a lot of questions:

• will it cause side effects to instantiate here?
• will we be instantiating a DuckDBClient too often?
• how expensive is it to instantiate one?
• is it possible to do it in a way that persists, instead?

Demo: