[AltStoreCore] Adds Pledge, PledgeReward, and PledgeTier

Allows us to cache pledges for current user, which can be used to determine if user has access to Patreon-only apps.

AltStoreCore/Model/Patreon/PledgeTier.swift

@@ -0,0 +1,46 @@
+//
+//  PledgeTier.swift
+//  AltStoreCore
+//
+//  Created by Riley Testut on 10/24/23.
+//  Copyright © 2023 Riley Testut. All rights reserved.
+//
+
+import Foundation
+import CoreData
+
+@objc(PledgeTier)
+public class PledgeTier: NSManagedObject, Fetchable
+{
+    /* Properties */
+    @NSManaged public private(set) var name: String
+    @NSManaged public private(set) var identifier: String
+    
+    @nonobjc public var amount: Decimal { _amount as Decimal } // In USD
+    @NSManaged @objc(amount) private var _amount: NSDecimalNumber
+    
+    /* Relationships */
+    @NSManaged public private(set) var pledge: Pledge?
+    
+    private override init(entity: NSEntityDescription, insertInto context: NSManagedObjectContext?)
+    {
+        super.init(entity: entity, insertInto: context)
+    }
+    
+    init(tier: PatreonAPI.Tier, context: NSManagedObjectContext)
+    {
+        super.init(entity: PledgeTier.entity(), insertInto: context)
+        
+        self.name = tier.name
+        self.identifier = tier.identifier
+        self._amount = tier.amount as NSDecimalNumber
+    }
+}
+
+public extension PledgeTier
+{
+    @nonobjc class func fetchRequest() -> NSFetchRequest<PledgeTier>
+    {
+        return NSFetchRequest<PledgeTier>(entityName: "PledgeTier")
+    }
+}