Add multi-instance state to item infos

- Add legacy resource for supported multi-instance apps that
  matches the current SystemUI resource of the same name, and will
  be removed as apps migrate to the V manifest property to declare
  multi-instance support
- Load the multi-instance state from PackageManager when the db is
  first loaded or when packages are updated
- The multi-instance check is then used to determine if an app pair
  can be saved (ie. whether the action can be shown)

Bug: 323112914
Test: atest NexusLauncherTests

Change-Id: I565b4bee4ab5f7040910306b1fd60a4fc3bf9a1c
diff --git a/res/values/config.xml b/res/values/config.xml
index 648a50c..a808a3f 100644
--- a/res/values/config.xml
+++ b/res/values/config.xml
@@ -223,4 +223,11 @@
     <string-array name="skip_private_profile_shortcut_packages" translatable="false">
         <item>com.android.settings</item>
     </string-array>
+
+    <!-- Legacy list of components supporting multiple instances.
+         DO NOT ADD TO THIS LIST.  Apps should use the PROPERTY_SUPPORTS_MULTI_INSTANCE_SYSTEM_UI
+         property to declare multi-instance support in V+. This resource should match the resource
+         of the same name in SystemUI. -->
+    <string-array name="config_appsSupportMultiInstancesSplit">
+    </string-array>
 </resources>