Function build 

pub fn build(
    agg: &AggCall,
    prefer_append_only: bool,
) -> Result<BoxedAggregateFunction>

Build an aggregate function.

If prefer_append_only is true, and both append-only and retractable implementations exist, the append-only version will be used.

NOTE: This function ignores argument indices, column_orders, filter and distinct in AggCall. Such operations should be done in batch or streaming executors.