Add countdown timers

[glowacki-dev]

To make game more dynamic, people use chess-style clocks during tournaments

[pastpatryk]

unfortunately the framework still doesn't support any server-side timers, so we will need to relay on clients on that (the same as in Pictionary)

[glowacki-dev]

This will work well enough for this use case. It seems like the timers are usually around 20 minutes for each player counted only during moves. It should be easy to keep track of it using time deltas between turn start and end