Add settings for frontend instance URL

Model/Accounts/InstancesBridge.swift

@@ -0,0 +1,38 @@
+
+import Defaults
+import Foundation
+
+struct InstancesBridge: Defaults.Bridge {
+    typealias Value = Instance
+    typealias Serializable = [String: String]
+
+    func serialize(_ value: Value?) -> Serializable? {
+        guard let value = value else {
+            return nil
+        }
+
+        return [
+            "app": value.app.rawValue,
+            "id": value.id,
+            "name": value.name,
+            "apiURL": value.apiURL,
+            "frontendURL": value.frontendURL ?? ""
+        ]
+    }
+
+    func deserialize(_ object: Serializable?) -> Value? {
+        guard
+            let object = object,
+            let app = VideosApp(rawValue: object["app"] ?? ""),
+            let id = object["id"],
+            let apiURL = object["apiURL"]
+        else {
+            return nil
+        }
+
+        let name = object["name"] ?? ""
+
+        let frontendURL: String? = object["frontendURL"]!.isEmpty ? nil : object["frontendURL"]
+        return Instance(app: app, id: id, name: name, apiURL: apiURL, frontendURL: frontendURL)
+    }
+}