Massively reorganize and clean up the whole Rust codebase (#478)

* Massively reorganize and clean up the whole Rust codebase

* Additional changes during code review

editor/src/input/input_mapper_message.rs

@@ -0,0 +1,16 @@
+use super::keyboard::Key;
+use crate::message_prelude::*;
+
+use serde::{Deserialize, Serialize};
+
+#[remain::sorted]
+#[impl_message(Message, InputMapper)]
+#[derive(PartialEq, Clone, Debug, Hash, Serialize, Deserialize)]
+pub enum InputMapperMessage {
+	#[child]
+	KeyDown(Key),
+	#[child]
+	KeyUp(Key),
+	MouseScroll,
+	PointerMove,
+}