feat: Add prop UIOptions.canvasActions.saveAsImage to show/hide save image button (#3662)

* feat: Add prop UIOptions.canvasActions.saveAsImage which implies whether the save as image dialog should be shown

* Add docs

* fix specs

src/constants.ts

@@ -135,6 +135,7 @@ export const DEFAULT_UI_OPTIONS: AppProps["UIOptions"] = {
     loadScene: true,
     saveToActiveFile: true,
     theme: true,
+    saveAsImage: true,
   },
 };