Add a Snake minigame to the file transfer screen

A basic Snake minigame you can play while your game is downloading ModernsupersonicFanServ_ServerpackMega+ManiaMusicpack+TorturedPlanetAndMysticRealmRepacks-3.8.24b-fix.wad at 35 kB/s.

Also, this fixes sounds and closed captions not being updated in the connection screen, which was very annoying since the captions would never disappear there.

I'm putting the graphics here for convenience (Big thanks to Chrispy for the snake's sprites): Snake.pk3