Convert DataFrames in dmod.metrics and dmod.evaluations to Polars

[christophertubbs]

Large scale evaluations will hit a bottleneck when it comes time to split datasets and start running metrics on small chunks of the overall dataset. Memory management will also become a problem.

To mitigate, this, logic needs to be written to convert the use of pandas dataframes to the frame logic provided by Polars. Some important dataframe operations can be ~400% faster in Polars and the memory footprint is smaller.

The majority of the work will come down to changing operations like fliters and grouping.