Additional column comparison checks

[benrutter]

At the moment, testing the average ratio and difference between columns is in place, which is handy. But would be useful to have some more "row specific" checks, where a ratio should never stray outside certain margins. I.e if you knew col_b should be more than 3 times col_a you might have:

- test: max_ratio_between_columns_should
  column: col_a
  other_column: col_b
  be_less_than_or_equal_to: 3

I think the nice polars/narwhal's API should make this pretty simple, ideally include:

• max_ratio_between_columns_should
• min_ratio_between_columns_should
• max_difference_between_columns_should
• min_difference_between_columns_should