Infected Cities update (new generated structure, mob, fungus block)

Introducing "fungus" block. It spreads to infect other blocks. When it's not submerged in water on all sides, it has a chance of turning a block that it is touching into a fungus block every minute. It can only be destroyed with fire or lava. If you break it with tools or your hands, it releases spores in an explosion, infecting the player and turning all touching blocks into fungus.

The "infected city" structure generates like a village, only: it's entirely underwater, it's primarily made of blue/green copper (rather than wood or stone), and various buildings/paths/etc have blocks of fungus embedded in them. You can find an infected city by examining sunken ships--the city will be connected by a tall column of fungus blocks to a half-submerged sunken ship that contains no treasure, only a fungus block capable of infecting other blocks of the ship. There's really good loot in the city, so there's a reason to risk exploring it.

The new mob is "the infected" which will spawn in the infected city. They look like if a villager or drowned was entirely converted to fungus. They are non-hostile, even when attacked. Attacking or killing them releases a spore explosion, converting blocks to fungus and infecting the player.

An infected player on land has a chance of turning touching blocks into fungus even faster than a fungus block. Also, entering a village is enough to start turning villagers into infected (like triggering a raid). There is no cure for villagers, only fire/lava.