Add snow rocks to planets (#17692)

Resources/Textures/Structures/Walls/rock.rsi/meta.json

@@ -1,7 +1,7 @@
 {
     "version": 1,
     "license": "CC-BY-SA-3.0",
-    "copyright": "https://github.com/Citadel-Station-13/Citadel-Station-13-RP/blob/817e7c1f225876b45891e3f06908e6d032f0a8bc/icons/turf/walls.dmiMade, rock_bananium made by brainfood1183 (github) for ss14",
+    "copyright": "https://github.com/Citadel-Station-13/Citadel-Station-13-RP/blob/817e7c1f225876b45891e3f06908e6d032f0a8bc/icons/turf/walls.dmi, rock_bananium made by brainfood1183 (github) for ss14, rock_snow and co from https://github.com/tgstation/tgstation/tree/e929cf39cded5207d63df1fa8521f41f2816b383",
     "size": {
         "x": 32,
         "y": 32
@@ -22,6 +22,21 @@
         {
             "name": "rock_west"
         },
+        {
+            "name": "rock_snow"
+        },
+        {
+            "name": "rock_snow_south"
+        },
+        {
+            "name": "rock_snow_east"
+        },
+        {
+            "name": "rock_snow_north"
+        },
+        {
+            "name": "rock_snow_west"
+        },
         {
             "name": "rock_artifact_fragment"
         },