Add DataFusion as a configurable substrait executor

[tokoko]

Substrait ODFVs are currently executed by acero (pyarrow.substrait), but support of substrait in acero is limited. I plan to add DataFusion as an alternative execution engine. I doubt there's too much of a difference between acero and datafusion at this point in terms of substrait support or performance, but I'm simply more familiar with DF and can fix issues on the DF side reasonably quickly unlike acero.

For now, the default engine will still be acero as it's bundled in pyarrow unlike datafusion which needs an additional dependency.