fix: Export TapConfig to make visible (#3323)

# Description
A few time ago I added TapConfig class. It allows us to config the tap
timing.
However, it's not exported. This PR fix this problem.

packages/flame/lib/input.dart

@@ -9,6 +9,7 @@ export 'src/components/input/joystick_component.dart';
 export 'src/components/input/sprite_button_component.dart';
 export 'src/events/game_mixins/multi_touch_drag_detector.dart';
 export 'src/events/game_mixins/multi_touch_tap_detector.dart';
+export 'src/events/tap_config.dart';
 export 'src/extensions/vector2.dart';
 export 'src/game/mixins/keyboard.dart';
 export 'src/gestures/detectors.dart';