Improves App ID counting + management

Fetches App ID count directly from Apple, and adds AppIDsViewController to view all App IDs for the logged-in account.

AltStore/Operations/FetchAppIDsOperation.swift

@@ -0,0 +1,73 @@
+//
+//  FetchAppIDsOperation.swift
+//  AltStore
+//
+//  Created by Riley Testut on 1/27/20.
+//  Copyright © 2020 Riley Testut. All rights reserved.
+//
+
+import Foundation
+
+import AltSign
+import AltKit
+
+import Roxas
+
+@objc(FetchAppIDsOperation)
+class FetchAppIDsOperation: ResultOperation<([AppID], NSManagedObjectContext)>
+{
+    let group: OperationGroup
+    let context: NSManagedObjectContext
+    
+    init(group: OperationGroup, context: NSManagedObjectContext = DatabaseManager.shared.persistentContainer.newBackgroundContext())
+    {
+        self.group = group
+        self.context = context
+        
+        super.init()
+    }
+    
+    override func main()
+    {
+        super.main()
+        
+        if let error = self.group.error
+        {
+            self.finish(.failure(error))
+            return
+        }
+        
+        guard
+            let team = self.group.signer?.team,
+            let session = self.group.session
+        else { return self.finish(.failure(OperationError.invalidParameters)) }
+                
+        ALTAppleAPI.shared.fetchAppIDs(for: team, session: session) { (appIDs, error) in
+            self.context.perform {
+                do
+                {
+                    let fetchedAppIDs = try Result(appIDs, error).get()
+                    
+                    guard let team = Team.first(satisfying: NSPredicate(format: "%K == %@", #keyPath(Team.identifier), team.identifier), in: self.context) else { throw OperationError.notAuthenticated }
+                    
+                    let fetchedIdentifiers = fetchedAppIDs.map { $0.identifier }
+                    
+                    let deletedAppIDsRequest = AppID.fetchRequest() as NSFetchRequest<AppID>
+                    deletedAppIDsRequest.predicate = NSPredicate(format: "%K == %@ AND NOT (%K IN %@)",
+                                                                 #keyPath(AppID.team), team,
+                                                                 #keyPath(AppID.identifier), fetchedIdentifiers)
+                    
+                    let deletedAppIDs = try self.context.fetch(deletedAppIDsRequest)
+                    deletedAppIDs.forEach { self.context.delete($0) }
+                    
+                    let appIDs = fetchedAppIDs.map { AppID($0, team: team, context: self.context) }
+                    self.finish(.success((appIDs, self.context)))
+                }
+                catch
+                {
+                    self.finish(.failure(error))
+                }
+            }
+        }
+    }
+}