feat: add MapSort expression support for Spark 4.0

Add native map_sort scalar function that sorts map entries by key in
ascending order, and wire it up via the Spark 4.0 CometExprShim so that
MapSort expressions are accelerated instead of falling back to Spark.
Re-enable all CometColumnarShuffleSuite map tests that were skipped for
Spark 4.0.

Closes #1941

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: andygrove

native/spark-expr/src/comet_scalar_funcs.rs

@@ -16,6 +16,7 @@
 // under the License.
 
 use crate::hash_funcs::*;
+use crate::map_funcs::spark_map_sort;
 use crate::math_funcs::abs::abs;
 use crate::math_funcs::checked_arithmetic::{checked_add, checked_div, checked_mul, checked_sub};
 use crate::math_funcs::log::spark_log;
@@ -191,6 +192,10 @@ pub fn create_comet_physical_fun_with_eval_mode(
             let func = Arc::new(crate::string_funcs::spark_get_json_object);
             make_comet_scalar_udf!("get_json_object", func, without data_type)
         }
+        "map_sort" => {
+            let func = Arc::new(spark_map_sort);
+            make_comet_scalar_udf!("spark_map_sort", func, without data_type)
+        }
         _ => registry.udf(fun_name).map_err(|e| {
             DataFusionError::Execution(format!(
                 "Function {fun_name} not found in the registry: {e}",

native/spark-expr/src/lib.rs

@@ -57,6 +57,7 @@ pub use bloom_filter::{BloomFilterAgg, BloomFilterMightContain};
 
 mod conditional_funcs;
 mod conversion_funcs;
+mod map_funcs;
 mod math_funcs;
 mod nondetermenistic_funcs;