Add handler for deferred execution of messages (#2951)

* Add Handler for defered execution of messages

* Cleanup

* Track graph execution id to associate messages with their corresponding execution id

* Rename ViewportReady -> NavigationReady

* Defer layer deselection

editor/src/messages/frontend/frontend_message.rs

@@ -59,7 +59,6 @@ pub enum FrontendMessage {
 		#[serde(rename = "commitDate")]
 		commit_date: String,
 	},
-	TriggerDelayedZoomCanvasToFitAll,
 	TriggerDownloadImage {
 		svg: String,
 		name: String,