Adds sealed class for widget info that can contain either appwidget info
or shortcut info.
Also kept the aosp config.xml empty to keep everything eligible for
featured
Bug: 370950552
Flag: com.android.launcher3.enable_widget_picker_refactor
Test: Open picker for homescreen and lockscreen hosts
Change-Id: Iceafc2c1234063b16421f90bf00cf96114e9870c
bb86bde284