Fix app pair launches with certain apps

This CL changes the way app pairs are saved. Previously, we saved the app pair using WorkspaceItemInfos directly from Recents, which caused certain apps to fail on launch because they weren't being launched with the correct Intent.

Now, we look up a proper launchable WorkspaceItemInfo from the AllAppsStore and save that to the app pair, which should fix the launch issues.

Bug: 323112914
Bug: 323110399
Test: Can launch Slides, Play Store, and Calendar when part of an app pair.
Flag: ACONFIG com.android.wm.shell.enable_app_pairs TEAMFOOD
Change-Id: I475afa1a237c50ffb0ffaf85af43912a803b8011