Move LogicalPlan tree_node modul (#9995)

Author: alamb

datafusion/expr/src/logical_plan/mod.rs

@@ -22,6 +22,7 @@ pub mod dml;
 mod extension;
 mod plan;
 mod statement;
+mod tree_node;
 
 pub use builder::{
     build_join_schema, table_scan, union, wrap_projection_for_join_if_necessary,

datafusion/expr/src/logical_plan/plan.rs

@@ -56,7 +56,7 @@ use datafusion_common::{
 
 // backwards compatibility
 use crate::display::PgJsonVisitor;
-use crate::tree_node::expr::transform_option_vec;
+use crate::tree_node::transform_option_vec;
 pub use datafusion_common::display::{PlanType, StringifiedPlan, ToStringifiedPlan};
 pub use datafusion_common::{JoinConstraint, JoinType};