Include server time with game state returned by the board stream endpoint

[johtso]

I'm trying to implement a custom client for playing games, and it occurred to me that it would be useful if there was a server time included with each object returned by the board stream API.

This would allow updating the client game clock with the correct time regardless of any hiccups / delay in getting the message.

GAME_TIME = REPORTED_GAME_TIME + (NOW - LICHESS_SERVER_TIME)

[ornicar]

the correct repository for this is ornicar/lila