Fix issue with tap-to-add on recycled WidgetCells

Updates BaseWidgetSheet to check if the last recorded widget cell
to show an add button is still showing an add button before deciding
how to handle the current click.

When a widget is recycled or loses focus, it will reset to the default
state of hiding the add button. However, BaseWidgetSheet still tracks
it. If that cell is clicked again after being reset, we want to show
the add button.

Bug: TODO
Test: manual
Flag: ACONFIG com.android.launcher3.enable_widget_tap_to_add TEAMFOOD
Change-Id: I4614674948a52b8908fabf5c0e5734bf76b9282b