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/arma/arma3/egg-arma3.json

@@ -8,7 +8,9 @@
     "name": "Arma 3",
     "author": "rehlmgaming@gmail.com",
     "description": "Experience true combat gameplay in a massive military sandbox. Deploying a wide variety of single- and multiplayer content, over 20 vehicles and 40 weapons, and limitless opportunities for content creation, this is the PC's premier military game. Authentic, diverse, open - Arma 3 sends you to war.",
-    "features": null,
+    "features": [
+        "steam_disk_space"
+    ],
     "images": [
         "ghcr.io\/parkervcp\/games:arma3"
     ],
@@ -236,4 +238,4 @@
             "rules": "required|string"
         }
     ]
-}
+}