Column Statistic improvment list after MVP

As we are wrapping up on the dataset level column statistics MVP, there are some high priority todo items: [ ] Support column stats generation for partial dataset. Currently the dataset will only be generated when all the files in the dataset has column stats written. A naive implementation is just to build the stats from the old fragment file rather than terminate early. [ ] Expose a Python API from the rust implementation. [ ] Exposing more stats in the discussion thread #4540

More could be found in the design doc