feat: custom node (#138)

* feat: custom node

* add zen template, expose $nodes and $root

* add custom handler to go and nodejs

* add support for python, improve bindings, add error to zen template

* fix: correct binding exports for nodejs and python

* fix benchmark

* improve rust api, trim template in zen templates

* update cargo action

* update expression version

* compile action

* fix action format

core/engine/src/handler/node.rs

@@ -11,7 +11,7 @@ pub struct NodeResponse {
     pub trace_data: Option<Value>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Serialize)]
 pub struct NodeRequest<'a> {
     pub input: Value,
     pub iteration: u8,