Code cleanup and refactoring to enhance consistency (#1695)

- Move message handler payload data into structs
- Organize the file structure used by `editor/src/messages/portfolio/document` `/node_graph` and `/graph_operation`
- Make derive attributes use `serde::Serialize, serde::Deserialize` consistently instead of `use serde::{Deserialize, Serialize};` imports
- Various other code cleanup and refactoring

node-graph/gcore/src/raster.rs

@@ -621,9 +621,8 @@ pub(crate) mod image;
 
 #[cfg(test)]
 mod test {
-	use crate::{ops::CloneNode, structural::Then, value::ValueNode, Node};
-
 	use super::*;
+	use crate::{ops::CloneNode, structural::Then, value::ValueNode, Node};
 
 	#[ignore]
 	#[test]