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/types.ts

@@ -230,6 +230,7 @@ type CanvasActions = {
   loadScene?: boolean;
   saveToActiveFile?: boolean;
   theme?: boolean;
+  saveAsImage?: boolean;
 };
 
 export type UIOptions = {