Function get_byte_array_buffers 

fn get_byte_array_buffers<O: OffsetSizeTrait>(
    data: &ArrayData,
) -> (Buffer, Buffer)

Returns the values and offsets [Buffer] for a ByteArray with offset type O

In particular, this handles re-encoding the offsets if they don’t start at 0, slicing the values buffer as appropriate. This helps reduce the encoded size of sliced arrays, as values that have been sliced away are not encoded