Add a default widget category provider that uses application category.

The category provider can be customized by any launcher via resource
override. For instance, one can override it to provide custom categories
using an allowlist or use a different mechanism such as query play
services.

We still need to get proper strings for categories from UX writer.

Bug: 318410881
Test: WidgetRecommendationCategoryProviderTest
Flag: ACONFIG com.android.launcher3.enable_categorized_widget_recommendations DEVELOPMENT
Change-Id: I5c4e0d22eaffc8254ddd54356f8c62f00e22a3c4