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

editor/src/messages/debug/debug_message.rs

@@ -1,9 +1,7 @@
 use crate::messages::prelude::*;
 
-use serde::{Deserialize, Serialize};
-
 #[impl_message(Message, Debug)]
-#[derive(PartialEq, Eq, Clone, Debug, Hash, Serialize, Deserialize)]
+#[derive(PartialEq, Eq, Clone, Debug, Hash, serde::Serialize, serde::Deserialize)]
 pub enum DebugMessage {
 	ToggleTraceLogs,
 	MessageOff,