Issues/1827 group-ungroup icons (#1956)

* show group and ungroup action-icon

* change group-icon visiblilty

don't show group if selected is only a single element or a single group of elements

Co-authored-by: rene_mbp <harryloveslearning@googlemail.com>

src/components/Actions.tsx

@@ -78,6 +78,8 @@ export const SelectedShapeActions = ({
           <div className="buttonList">
             {renderAction("duplicateSelection")}
             {renderAction("deleteSelectedElements")}
+            {renderAction("group")}
+            {renderAction("ungroup")}
           </div>
         </fieldset>
       )}