Add Farlands as an official world generation type (like superflat)

Since the ENABLE_FARLANDS debug flag was added in 26.3 Pre-Release 1, I suggest adding a new Farlands World type to the world creation menu. This would give the players a possibility for a more interesting and/or chaotic survival experience without external modifications of the game. It could work by creating Farlands at zero coordinates, or a bit away from them so the player can get starter resources easier.