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/Holiday Stuff/Christmas/2004/Mistletoe.cs

@@ -104,7 +104,6 @@ public partial class MistletoeAddon : Item, IDyable, IAddon
 
         if (from.InRange(GetWorldLocation(), 3))
         {
-            from.CloseGump<MistletoeAddonGump>();
             from.SendGump(new MistletoeAddonGump(from, this));
         }
         else
@@ -118,6 +117,8 @@ public partial class MistletoeAddon : Item, IDyable, IAddon
         private readonly MistletoeAddon _addon;
         private readonly Mobile _from;
 
+        public override bool Singleton => true;
+
         public MistletoeAddonGump(Mobile from, MistletoeAddon addon) : base(150, 50)
         {
             _from = from;

Projects/UOContent/Holiday Stuff/Christmas/2010/Addons/FireFliesDeed.cs

@@ -46,7 +46,6 @@ public partial class Fireflies : Item, IAddon
 
         if (house?.IsOwner(from) == true)
         {
-            from.CloseGump<RewardDemolitionGump>();
             // Do you wish to re-deed this decoration?
             from.SendGump(new RewardDemolitionGump(this, 1049783));
         }
@@ -86,7 +85,6 @@ public partial class FirefliesDeed : Item
             return;
         }
 
-        from.CloseGump<FacingGump>();
         from.SendGump(new FacingGump(this, from));
     }
 
@@ -95,6 +93,8 @@ public partial class FirefliesDeed : Item
         private readonly FirefliesDeed _deed;
         private readonly Mobile _placer;
 
+        public override bool Singleton => true;
+
         public FacingGump(FirefliesDeed deed, Mobile player) : base(150, 50)
         {
             _deed = deed;