Updated NETunnelProvider save format

Signed-off-by: Eric Kuck <eric@bluelinelabs.com>

WireGuard/Shared/Model/Legacy/LegacyTunnelConfiguration.swift

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: MIT
+// Copyright © 2018 WireGuard LLC. All Rights Reserved.
+
+import Foundation
+
+final class LegacyTunnelConfiguration: Codable {
+    let interface: LegacyInterfaceConfiguration
+    let peers: [LegacyPeerConfiguration]
+}
+
+extension LegacyTunnelConfiguration {
+    var migrated: TunnelConfiguration {
+        return TunnelConfiguration(interface: interface.migrated, peers: peers.migrated)
+    }
+}