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

libraries/bezier-rs/src/bezier/lookup.rs

@@ -208,6 +208,7 @@ impl Bezier {
 #[cfg(test)]
 mod tests {
 	use super::*;
+
 	#[test]
 	fn test_evaluate() {
 		let p1 = DVec2::new(3., 5.);