Refactor BackupParams coding

Sources/XXMessengerClient/Messenger/Functions/MessengerRestoreBackup.swift

@@ -42,9 +42,8 @@ extension MessengerRestoreBackup {
         sessionPassword: password,
         backupFileContents: backupData
       )
-      let decoder = JSONDecoder()
       let paramsData = report.params.data(using: .utf8)!
-      let params = try decoder.decode(BackupParams.self, from: paramsData)
+      let params = try BackupParams.decode(paramsData)
       let cMix = try env.loadCMix(
         storageDir: storageDir,
         password: password,

Sources/XXMessengerClient/Utils/BackupParams.swift

 import Foundation
 
-public struct BackupParams: Equatable, Codable {
+public struct BackupParams: Equatable {
   public init(
     username: String,
     email: String?,
@@ -15,3 +15,13 @@ public struct BackupParams: Equatable, Codable {
   public var email: String?
   public var phone: String?
 }
+
+extension BackupParams: Codable {
+  public static func decode(_ data: Data) throws -> Self {
+    try JSONDecoder().decode(Self.self, from: data)
+  }
+
+  public func encode() throws -> Data {
+    try JSONEncoder().encode(self)
+  }
+}