Previously, output partitions were labelled sequentially as `part.{i}.parquet` for i in 0...n, where n was the number of unique H3 parent cells in the dataset, one part per parent.
To make this easier to consume, we now label these as `{h3parent}.parquet`, which allows users to select a particular partition based on a H3 cell without having to do anything except list the output directory. The output order is the same since the sort order was already based on a lexicographic order of the H3 cells.