runVpnService method
Requests permission from user then starts vpn service
Returns whether user grants permission.
apps is a list of android app's name. Eg. com.google.youtube
It isn't safe to call from background. Calling from Isolate may be result of unknown behavior.
Implementation
@override
Future<bool> runVpnService(List<String> apps) async => (await methodChannel
.invokeMethod<bool>("startVpn", {"allowedApps": apps}))!;