[suggestion] Add premium player support

[ultard]

I would really like to be able to log in without a login if the player logged in through a licensed account, and if someone tried to log in without it on the same account, then ask for a password

I propose to add to the config such strings:

premium-auth-check: true  
premium-authentication-steps:
  - VK_LINK
  - TELEGRAM_LINK
  - GOOGLE_LINK
  - ENTER_SERVER

I would be very grateful if you could perform this

[bivashy]

Yeah, but one thing that i should note: player should manually enable license "enter", like in LibreLogin, because it`ll be more easy to implement.

Also thanks for providing idea with "additional steps" for premium players.