Add window title and icon

gui/ui/app.slint

@@ -323,8 +323,12 @@ component ShopView inherits VerticalLayout {
 
 export component App inherits Window {
 
+    title: "Inköpslista";
+    icon: @image-url("../images/icon.svg");
+
     preferred-height: 700px;
     preferred-width: 480px;
+
     TabWidget {
         Tab {
             title: "Add";