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

desktop/src/app.rs

@@ -21,6 +21,7 @@ use crate::persist::PersistentData;
 use crate::preferences;
 use crate::render::{RenderError, RenderState};
 use crate::window::Window;
+use crate::workspace_layout;
 use crate::wrapper::messages::{DesktopFrontendMessage, DesktopWrapperMessage, InputMessage, MouseKeys, MouseState, Preferences};
 use crate::wrapper::{DesktopWrapper, NodeGraphExecutionResult, WgpuContext, serialize_frontend_messages};
 
@@ -304,6 +305,15 @@ impl App {
 				let message = DesktopWrapperMessage::LoadPreferences { preferences };
 				responses.push(message);
 			}
+			DesktopFrontendMessage::PersistenceWriteWorkspaceLayout { workspace_layout: layout } => {
+				workspace_layout::write(&layout);
+			}
+			DesktopFrontendMessage::PersistenceLoadWorkspaceLayout => {
+				if let Some(workspace_layout) = workspace_layout::read() {
+					let message = DesktopWrapperMessage::LoadWorkspaceLayout { workspace_layout };
+					responses.push(message);
+				}
+			}
 			DesktopFrontendMessage::PersistenceLoadCurrentDocument => {
 				if let Some((id, document)) = self.persistent_data.current_document() {
 					let message = DesktopWrapperMessage::LoadDocument {