Add support for persistent storage of panel layouts, sizes, and active tabs (#4017)

* Add persistence to panel layouts

* Fix and persist the Window > Focus Document mode

* Add a Window > Reset Workspace action

* workspace_layout.json -> workspace_layout.ron

* Fix native app hole punch

* Cleanup review pass

editor/src/messages/frontend/frontend_message.rs

@@ -127,12 +127,17 @@ pub enum FrontendMessage {
 	TriggerLoadRestAutoSaveDocuments,
 	TriggerOpenLaunchDocuments,
 	TriggerLoadPreferences,
+	TriggerLoadWorkspaceLayout,
 	TriggerOpen,
 	TriggerImport,
 	TriggerSavePreferences {
 		#[tsify(type = "unknown")]
 		preferences: PreferencesMessageHandler,
 	},
+	TriggerSaveWorkspaceLayout {
+		#[serde(rename = "workspaceLayout")]
+		workspace_layout: WorkspacePanelLayout,
+	},
 	TriggerSaveActiveDocument {
 		#[serde(rename = "documentId")]
 		document_id: DocumentId,