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/pavlov_vr/egg-pavlov-v-r.json

@@ -8,7 +8,9 @@
     "name": "Pavlov VR",
     "author": "admin@devil.wtf",
     "description": "Pavlov VR is a multiplayer shooter in VR with heavy focus on community features. Realistic reloading features and fast paced combat as part of the core experience. Play the #1 most popular VR shooter on PC today.",
-    "features": null,
+    "features": [
+        "steam_disk_space"
+    ],
     "images": [
         "quay.io\/parkervcp\/pterodactyl-images:debian_source"
     ],
@@ -74,4 +76,4 @@
             "rules": "required|boolean"
         }
     ]
-}
+}