Added locking of configs

[approbax]

Hi Dear developer
first of all I would like to sincerely thank you for helping people to reach freedom and bypass censorship.
I have been using V2rayNG app for a while and I think one thing it's missing is the lock feature. It would be awesome if you could add the feature that allow us to lock the config files using your app. It's a great feature that allow us to hide our domain and sni and also the port we are using from other people.