Function from_table_scan   
pub fn from_table_scan(
    producer: &mut impl SubstraitProducer,
    scan: &TableScan,
) -> Result<Box<Rel>, DataFusionError>pub fn from_table_scan(
    producer: &mut impl SubstraitProducer,
    scan: &TableScan,
) -> Result<Box<Rel>, DataFusionError>