LoadMapRule grid storage rework (#28210)

*

Content.Server/GameTicking/Rules/Components/LoadMapRuleComponent.cs

@@ -1,8 +1,6 @@
+using Content.Server.GameTicking.Rules;
 using Content.Server.Maps;
 using Content.Shared.GridPreloader.Prototypes;
-using Content.Shared.Storage;
-using Content.Shared.Whitelist;
-using Robust.Shared.Map;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Utility;
 
@@ -10,25 +8,27 @@ namespace Content.Server.GameTicking.Rules.Components;
 
 /// <summary>
 /// This is used for a game rule that loads a map when activated.
+/// Works with <see cref="RuleGridsComponent"/>.
 /// </summary>
-[RegisterComponent]
+[RegisterComponent, Access(typeof(LoadMapRuleSystem))]
 public sealed partial class LoadMapRuleComponent : Component
 {
-    [DataField]
-    public MapId? Map;
-
+    /// <summary>
+    /// A <see cref="GameMapPrototype"/> to load on a new map.
+    /// </summary>
     [DataField]
     public ProtoId<GameMapPrototype>? GameMap;
 
+    /// <summary>
+    /// A map path to load on a new map.
+    /// </summary>
     [DataField]
     public ResPath? MapPath;
 
+    /// <summary>
+    /// A <see cref="PreloadedGridPrototype"/> to move to a new map.
+    /// If there are no instances left nothing is done.
+    /// </summary>
     [DataField]
     public ProtoId<PreloadedGridPrototype>? PreloadedGrid;
-
-    [DataField]
-    public List<EntityUid> MapGrids = new();
-
-    [DataField]
-    public EntityWhitelist? SpawnerWhitelist;
 }