Minor Description
SparkPlan's vectorType's attribute can be used to specialize codegen however BatchScanExecBase does not override this so we DSv2 sources do not get any benefit of concrete class dispatch.
This proposes adding an override to BatchScanExecBase which delegates to a new default method on PartitionReaderFactory to expose vectoryTypes:
{{
default Optional<Iterable<String>> getVectorTypes()
}}
