Fix visibility of swap_hash_join (#13899)

Author: alamb

datafusion/core/src/physical_optimizer/join_selection.rs

@@ -176,7 +176,7 @@ fn swap_join_projection(
 /// This function swaps the inputs of the given join operator.
 /// This function is public so other downstream projects can use it
 /// to construct `HashJoinExec` with right side as the build side.
-pub(crate) fn swap_hash_join(
+pub fn swap_hash_join(
     hash_join: &HashJoinExec,
     partition_mode: PartitionMode,
 ) -> Result<Arc<dyn ExecutionPlan>> {