[PS] Do not use AppInfo and use PrivateSpaceInstallAppButtonInfo instead.

BaseAllAppsAdapter.AdapterItem's itemInfo needs to be an AppInfo. Create PrivateSpaceInstallAppButtonInfo extending from AppInfo and use different itemType (AppInfo has default itemType ITEM_TYPE_APPLICATION). In this case, shortcuts is disabled in ShortcutUtil#supportsShortcuts because `isApp` is false (https://source.corp.google.com/h/googleplex-android/platform/superproject/main/+/main:packages/apps/Launcher3/src/com/android/launcher3/util/ShortcutUtil.java;l=30?q=shortcututil&sq=repo:googleplex-android%2Fplatform%2Fsuperproject%2Fmain%20b:main).

After the fix, long click on Install button quits Toast, which is the same with drag action on the button.

Since we have a specific itemType for PS install button now, the previous `FLAG_PRIVATE_SPACE_INSTALL_APP` is no longer needed. Remove it.

Bug: 324211283
Test: manual
Flag: aconfig com.google.android.apps.nexuslauncher.private_space_app_installer_button trunkfood
Change-Id: Ic5d4284afb93cef77f2ad8f0c1588523e0ed3ae3

src/com/android/launcher3/model/data/ItemInfoWithIcon.java

@@ -120,11 +120,6 @@ public abstract class ItemInfoWithIcon extends ItemInfo {
      */
     public static final int FLAG_ARCHIVED = 1 << 14;
 
-    /**
-     * Flag indicating it's the Private Space Install App icon.
-     */
-    public static final int FLAG_PRIVATE_SPACE_INSTALL_APP = 1 << 15;
-
     /**
      * Status associated with the system state of the underlying item. This is calculated every
      * time a new info is created and not persisted on the disk.