Pin un-rotated infested_stone variants to match stone.json

[BharathASL]

pack_template/assets/minecraft/blockstates/stone.json pins stone to a single un-rotated minecraft:block/stone variant, but there is no override for infested_stone. Vanilla infested_stone.json (checked against the 1.21.6 client jar) still lists four weighted-random variants: stone, stone_mirrored, stone with y: 180 and stone_mirrored with y: 180.

Infested stone generates in veins inside ordinary stone, so about 3 in 4 infested blocks render mirrored or rotated next to pinned stone. That breaks the texture continuity the stone override is meant to guarantee, and it makes silverfish blocks identifiable by sight.

What to do

Add pack_template/assets/minecraft/blockstates/infested_stone.json with the same single variant as stone.json:

{
  "variants": {
    "": [
      {
        "model": "minecraft:block/stone"
      }
    ]
  }
}

infested_deepslate has the same gap relative to deepslate.json, and is fixed in #232.