Prioritizes app refresh order

Tries to refresh apps that are about to expire first, and then always refreshes AltStore itself last, since refreshing AltStore means that the app will quit.

AltStore/Operations/AppOperationContext.swift

@@ -0,0 +1,35 @@
+//
+//  Contexts.swift
+//  AltStore
+//
+//  Created by Riley Testut on 6/20/19.
+//  Copyright © 2019 Riley Testut. All rights reserved.
+//
+
+import Foundation
+import CoreData
+import Network
+
+class AppOperationContext
+{
+    var appIdentifier: String
+    var group: OperationGroup
+        
+    var installedApp: InstalledApp? {
+        didSet {
+            self.installedAppContext = self.installedApp?.managedObjectContext
+        }
+    }
+    private var installedAppContext: NSManagedObjectContext?
+    
+    var resignedFileURL: URL?
+    var connection: NWConnection?
+    
+    var error: Error?
+    
+    init(appIdentifier: String, group: OperationGroup)
+    {
+        self.appIdentifier = appIdentifier
+        self.group = group
+    }
+}