Show the category name in the toolbar when clicking a category. am: 0088bca696 am: 576b0cc295

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/WallpaperPicker2/+/11613156

Change-Id: I46818549e6cbbdf9474e2d664b172cd5ff01b78d