Event broadcasting system (#692)

* broadcast system implemented but not everywhere

* unused types

* code review with keavon

* - optional signal mappings
- tool.rs simplification

* Cleanup

* reduced code duplication in `tool.rs`

* ran cargo fmt

* code review changes

* fix merge error

Co-authored-by: Keavon Chambers <keavon@keavon.com>

editor/src/communication/message.rs

@@ -23,6 +23,8 @@ pub enum Message {
 	#[remain::unsorted]
 	NoOp,
 	#[child]
+	Broadcast(BroadcastMessage),
+	#[child]
 	Dialog(DialogMessage),
 	#[child]
 	Frontend(FrontendMessage),