Feature: Hint viewer (#666)

* Add Hint viewer

- Add hints for arrows and lines
- Add hints for resizing elements

* Swap priority of multi mode and resize mode in Hint Viewer

* Remove dangling locales from public

* Add shortcut to hide hints

* Change hint texts and show resize hint ONLY during resizing

* Remove hints toggling

src/appState.ts

@@ -26,6 +26,7 @@ export function getDefaultAppState(): AppState {
     cursorY: 0,
     scrolledOutside: false,
     name: DEFAULT_PROJECT_NAME,
+    isResizing: false,
   };
 }