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/Multis/Houses/HouseSign.cs

@@ -263,7 +263,6 @@ public partial class HouseSign : Item
             }
             else
             {
-                from.CloseGump<VendorInventoryGump>();
                 from.SendGump(new VendorInventoryGump(sign.Owner, from));
             }
         }