New test for reading and verifying all of the TPCDS data.
change layout of var length vectors to match parquet old format.
Single column varchar is matching between the two parquet readers with the new faster layout that matches parquet format.

This needs to be enhanced to use a start/end rather than just a constant buffer between each value, the issue is that no data (including a length) is given in the parquet file if the data is null. This requires us to specify a start and end.
WIP - trying to figure out a minimal set of columns that produces the problem.