[AltStoreCore] Refactors core AltStore logic into AltStoreCore framework

AltStoreCore will contain all shared AltStore code between AltStore and any app extensions. Initially, it includes all AltStore model logic.

AltStore/Settings/PatreonViewController.swift

@@ -10,6 +10,7 @@ import UIKit
 import SafariServices
 import AuthenticationServices
 
+import AltStoreCore
 import Roxas
 
 extension PatreonViewController

AltStore/Settings/RefreshAttemptsViewController.swift

@@ -8,6 +8,7 @@
 
 import UIKit
 
+import AltStoreCore
 import Roxas
 
 @objc(RefreshAttemptTableViewCell)

AltStore/Settings/SettingsViewController.swift

@@ -10,6 +10,8 @@ import UIKit
 import SafariServices
 import MessageUI
 
+import AltStoreCore
+
 extension SettingsViewController
 {
     fileprivate enum Section: Int, CaseIterable