Add Lichess as a Profile Connection

With the recent explosion of chess on Twitch, allowing users to authenticate through Lichess would enable lots of fun bot functionality, for example:

- Allowing users to play rated games on their own accounts (so they can be saved and analyzed) through chat commands

 - Playing blindfold games through voice channels against real human opponents (not implemented in a usable way anywhere else)

PLEASE add this feature and the chess community will thank you!