feat: add steam_disk_space egg feature to SteamCMD eggs

A new egg feature modal was introduced in Panel v1.7.0 triggering when server has run out of disk space to provide more user-friendly instructions to both admins and normal users. This is unique to SteamCMD specific errors.

game_eggs/steamcmd_servers/craftopia/egg-craftopia.json

@@ -8,7 +8,9 @@
     "name": "Craftopia",
     "author": "info@goover.de",
     "description": "Craftopia is the brand new multiplayer survival action game made in Japan. We combined many features we find enjoyable, such as hunting, farming, hack-and-slash, building, automation to develop this game.",
-    "features": null,
+    "features": [
+        "steam_disk_space"
+    ],
     "images": [
         "ghcr.io\/parkervcp\/games:source"
     ],
@@ -56,4 +58,4 @@
             "rules": "required|string|max:50"
         }
     ]
-}
+}