Superflat worlds containing blocks with different associated blockitems display name of item instead of name of block

When creating a superflat world out of blocks which do not have direct item counterparts, but do have dedicated items to place them (such as fluids and crops), since they do not have an actual block icon the item is displayed instead. However, the name of the item is also displayed as well, which can lead to nonsensical results; for example, a superflat world with minecraft:water in it is a world with a layer of water, not a world with a layer of water buckets.

Fire appears to be an exception to this rule; it is displayed as air instead of flint and steel.

As all blocks should have translation strings and associated names, a fix would be to only display the item in the inventory slot to the left, and the actual name of the block to the right. This would also fix the names for MC-48058.

To reproduce, use the following preset:

minecraft:carrots,minecraft:potatoes,minecraft:beetroots,minecraft:wheat,minecraft:melon_stem,minecraft:pumpkin_stem,minecraft:tripwire,minecraft:water,minecraft:lava,minecraft:sweet_berry_bush,minecraft:cocoa,minecraft:fire;minecraft:swamp;village

This will probably crash the world shortly after load due to invalid block positions, however the world can be subsequently recreated to test the bug without entering the world.