feat(element/selection): Element implementation for selecting an enum variant

src/app.zig

@@ -418,6 +418,7 @@ pub fn App(comptime E: type) type {
         pub const Progress = element.Progress(Event, Queue);
         pub const RadioButton = element.RadioButton(Event);
         pub const Scrollable = element.Scrollable(Event);
+        pub const Selection = element.Selection(Event);
         pub const Queue = queue.Queue(Event, 256);
     };
 }