Make comparisons/sort-by more 'global' (#4500)

* Make comparisons/sort-by more 'global'

* Let custom values do their own comparisons

crates/nu-command/src/dataframe/eager/drop_duplicates.rs

@@ -39,11 +39,11 @@ impl Command for DropDuplicates {
                 NuDataFrame::try_from_columns(vec![
                     Column::new(
                         "a".to_string(),
-                        vec![Value::test_int(1), Value::test_int(3)],
+                        vec![Value::test_int(3), Value::test_int(1)],
                     ),
                     Column::new(
                         "b".to_string(),
-                        vec![Value::test_int(2), Value::test_int(4)],
+                        vec![Value::test_int(4), Value::test_int(2)],
                     ),
                 ])
                 .expect("simple df for test should not fail")

crates/nu-command/src/dataframe/eager/mod.rs

@@ -82,6 +82,7 @@ pub fn add_eager_decls(working_set: &mut StateWorkingSet) {
         DataTypes,
         DescribeDF,
         DropDF,
+        DropDuplicates,
         DropNulls,
         Dummies,
         FilterWith,