feat: passthrough nodes (#261)

* feat: passthrough nodes

* update bindings

* update model

* update exclusion

* fix merge strategy

* fix

* fix merge

* add tests

* fix walk

* fix merge

* fix

* fix: add tests

* fix types

---------

Co-authored-by: Ivan Miletic <vnmiletic@gmail.com>

core/engine/src/handler/node.rs

@@ -2,6 +2,7 @@ use crate::model::DecisionNode;
 use serde::{Deserialize, Serialize};
 use serde_json::Value;
 use std::fmt::{Display, Formatter};
+use std::sync::Arc;
 use thiserror::Error;
 use zen_expression::variable::Variable;
 
@@ -12,11 +13,11 @@ pub struct NodeResponse {
     pub trace_data: Option<Value>,
 }
 
-#[derive(Debug, Serialize)]
-pub struct NodeRequest<'a> {
+#[derive(Debug, Serialize, Clone)]
+pub struct NodeRequest {
     pub input: Variable,
     pub iteration: u8,
-    pub node: &'a DecisionNode,
+    pub node: Arc<DecisionNode>,
 }
 
 #[derive(Error, Debug)]