feat: Moves gumps out of the core (#1916)

> [!Important]
> **Developer Note**
> This code change will **completely move gumps out of the core**


### Summary

- Adds `GetGumps()` convenience which exposes methods to Find/Close/Send multiple gumps. This helper is a performance improvement by eliminating the Dictionary<Player, List> lookup for gumps.

Projects/UOContent/Items/Containers/TreasureMapChest.cs

@@ -433,7 +433,6 @@ public partial class TreasureMapChest : LockableContainer
             return;
         }
 
-        from.CloseGump<RemoveGump>();
         from.SendGump(new RemoveGump(from, this));
     }
 
@@ -453,6 +452,8 @@ public partial class TreasureMapChest : LockableContainer
         private readonly TreasureMapChest _chest;
         private readonly Mobile _from;
 
+        public override bool Singleton => true;
+
         public RemoveGump(Mobile from, TreasureMapChest chest) : base(15, 15)
         {
             _from = from;