Zip importing: importFromFile should take a completionHandler

Deletion of the being-imported file should be done in the
completionHandler.

Signed-off-by: Roopesh Chander <roop@roopc.net>

WireGuard/WireGuard/UI/iOS/AppDelegate.swift

@@ -27,8 +27,9 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     }
 
     func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey: Any] = [:]) -> Bool {
-        mainVC?.tunnelsListVC?.importFromFile(url: url)
-        _ = FileManager.deleteFile(at: url)
+        mainVC?.tunnelsListVC?.importFromFile(url: url) {
+            _ = FileManager.deleteFile(at: url)
+        }
         return true
     }