Removed the polars dtypes command (#12577)

# Description
The polars dtype command is largerly redundant since the introduction of
the schema command. The schema command also has the added benefit that
it's output can be used as a parameter to other schema commands:

```nushell
[[a b]; [5 6] [5 7]] | polars into-df -s ($df | polars schema
```

# User-Facing Changes
`polars dtypes` has been removed. Users should use `polars schema`
instead.

Co-authored-by: Jack Wright <jack.wright@disqo.com>

crates/nu_plugin_polars/src/dataframe/eager/dtypes.rs

@@ -1,111 +0,0 @@
-use crate::PolarsPlugin;
-
-use super::super::values::{Column, CustomValueSupport, NuDataFrame};
-use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
-use nu_protocol::{
-    Category, Example, LabeledError, PipelineData, ShellError, Signature, Span, Type, Value,
-};
-
-#[derive(Clone)]
-pub struct DataTypes;
-
-impl PluginCommand for DataTypes {
-    type Plugin = PolarsPlugin;
-
-    fn name(&self) -> &str {
-        "polars dtypes"
-    }
-
-    fn usage(&self) -> &str {
-        "Show dataframe data types."
-    }
-
-    fn signature(&self) -> Signature {
-        Signature::build(self.name())
-            .input_output_type(
-                Type::Custom("dataframe".into()),
-                Type::Custom("dataframe".into()),
-            )
-            .category(Category::Custom("dataframe".into()))
-    }
-
-    fn examples(&self) -> Vec<Example> {
-        vec![Example {
-            description: "Dataframe dtypes",
-            example: "[[a b]; [1 2] [3 4]] | polars into-df | polars dtypes",
-            result: Some(
-                NuDataFrame::try_from_columns(
-                    vec![
-                        Column::new(
-                            "column".to_string(),
-                            vec![Value::test_string("a"), Value::test_string("b")],
-                        ),
-                        Column::new(
-                            "dtype".to_string(),
-                            vec![Value::test_string("i64"), Value::test_string("i64")],
-                        ),
-                    ],
-                    None,
-                )
-                .expect("simple df for test should not fail")
-                .into_value(Span::test_data()),
-            ),
-        }]
-    }
-
-    fn run(
-        &self,
-        plugin: &Self::Plugin,
-        engine: &EngineInterface,
-        call: &EvaluatedCall,
-        input: PipelineData,
-    ) -> Result<PipelineData, LabeledError> {
-        command(plugin, engine, call, input).map_err(LabeledError::from)
-    }
-}
-
-fn command(
-    plugin: &PolarsPlugin,
-    engine: &EngineInterface,
-    call: &EvaluatedCall,
-    input: PipelineData,
-) -> Result<PipelineData, ShellError> {
-    let df = NuDataFrame::try_from_pipeline_coerce(plugin, input, call.head)?;
-
-    let mut dtypes: Vec<Value> = Vec::new();
-    let names: Vec<Value> = df
-        .as_ref()
-        .get_column_names()
-        .iter()
-        .map(|v| {
-            let dtype = df
-                .as_ref()
-                .column(v)
-                .expect("using name from list of names from dataframe")
-                .dtype();
-
-            let dtype_str = dtype.to_string();
-
-            dtypes.push(Value::string(dtype_str, call.head));
-
-            Value::string(*v, call.head)
-        })
-        .collect();
-
-    let names_col = Column::new("column".to_string(), names);
-    let dtypes_col = Column::new("dtype".to_string(), dtypes);
-
-    let df = NuDataFrame::try_from_columns(vec![names_col, dtypes_col], None)?;
-    df.to_pipeline_data(plugin, engine, call.head)
-}
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    use crate::test::test_polars_plugin_command;
-
-    #[test]
-    fn test_examples() -> Result<(), ShellError> {
-        test_polars_plugin_command(&DataTypes)
-    }
-}

crates/nu_plugin_polars/src/dataframe/eager/mod.rs

@@ -4,7 +4,6 @@ mod columns;
 mod drop;
 mod drop_duplicates;
 mod drop_nulls;
-mod dtypes;
 mod dummies;
 mod filter_with;
 mod first;
@@ -41,7 +40,6 @@ pub use columns::ColumnsDF;
 pub use drop::DropDF;
 pub use drop_duplicates::DropDuplicates;
 pub use drop_nulls::DropNulls;
-pub use dtypes::DataTypes;
 pub use dummies::Dummies;
 pub use filter_with::FilterWith;
 pub use first::FirstDF;
@@ -73,7 +71,6 @@ pub(crate) fn eager_commands() -> Vec<Box<dyn PluginCommand<Plugin = PolarsPlugi
         Box::new(AppendDF),
         Box::new(CastDF),
         Box::new(ColumnsDF),
-        Box::new(DataTypes),
         Box::new(DropDF),
         Box::new(DropDuplicates),
         Box::new(DropNulls),