Refactors the safe Christmas trees to use a safe present subtype by way of a blacklist (#5027)

## About The Pull Request
Updates the safe tree to use a proper blacklist instead of being boring
and just giving bloodthirsty spacemen and women toys... They were good
all year, they crave violence. This replaces the round start Christmas
trees with the safe trees, which no longer only give out toys, but also
no longer give out admin/debug gear. A compromise for all, just in time
for Christmas!

The Christmas event present spawns have all been replaced with the safe
variants that utilize the blacklist, the other means of acquiring
presents have been left untouched.
## Why It's Good For The Game
People not getting admin tools out of Christmas presents and causing
headaches for staff is probably good for the game, maybe.
## Proof Of Testing
<details>
<summary>Screenshots/Videos</summary>
<img width="418" height="452" alt="image"
src="https://github.com/user-attachments/assets/df6554ee-084a-40c2-9592-94c88f6569c4"
/>

</details>

## Changelog
🆑 xPokee, LT3
balance: All Christmas event presents have been replaced with the safe
variants.
refactor: The safe Christmas tree subtype now uses a blacklist instead
of just giving toys.
admin: Added a new verb in the 'game' tab to blacklist presents on the
fly.
/🆑

code/modules/clothing/outfits/event.dm

@@ -5,7 +5,7 @@
 	suit = /obj/item/clothing/suit/space/santa
 	back = /obj/item/storage/backpack/santabag
 	backpack_contents = list(
-		/obj/item/gift/anything = 5,
+		/obj/item/gift/mostly_anything = 5, // BUBBER EDIT - Previous: /obj/item/gift/anything
 	)
 	gloves = /obj/item/clothing/gloves/color/red
 	head = /obj/item/clothing/head/helmet/space/santahat/beardless

code/modules/events/holiday/xmas.dm

@@ -53,7 +53,7 @@
 	/// Christmas tree, no presents included.
 	var/festive_tree = /obj/structure/flora/tree/pine/xmas
 	/// Christmas tree, presents included.
-	var/christmas_tree = /obj/structure/flora/tree/pine/xmas/presents
+	var/christmas_tree = /obj/structure/flora/tree/pine/xmas/presents/safe // BUBBER EDIT - Previous: /obj/structure/flora/tree/pine/xmas/presents
 
 /obj/effect/spawner/xmastree/Initialize(mapload)
 	. = ..()

code/modules/holiday/holidays.dm

@@ -992,7 +992,7 @@ GLOBAL_LIST_INIT(holiday_mail, list())
 	GLOB.maintenance_loot += list(
 		list(
 			/obj/item/clothing/head/costume/santa = 1,
-			/obj/item/gift/anything = 1,
+			/obj/item/gift/mostly_anything = 1, // BUBBER EDIT - Previous: /obj/item/gift/anything
 			/obj/item/toy/xmas_cracker = 3,
 		) = maint_holiday_weight,
 	)