[AltStore] Adds ALTAppGroup Info.plist entry for apps in app groups

This allows the apps to query at runtime what app groups they should actually use due to bundle identifiers changing.

AltKit/Bundle+AltStore.swift

@@ -13,6 +13,7 @@ public extension Bundle
     struct Info
     {
         public static let deviceID = "ALTDeviceID"
+        public static let appGroups = "ALTAppGroups"
         
         public static let urlTypes = "CFBundleURLTypes"
     }