Updating launcher settings so that they become split-screen

Following this guide:
https://developer.android.com/guide/topics/large-screens/activity-embedding#extract_an_activity_from_a_split_to_full_window

Bug: 204463748
Test: Open the settings app and open multiple settings, for now
only the options inside of the launcher3 package work
Flag: ACONFIG com.android.launcher3.Flags.enableTwoPaneLauncherSettings DEVELOPMENT

Change-Id: Ie6a9eb3760171da92d94cf06376127b02afff8df