moves abstract_type up to datum, spawners wont spawn them (#92909)

## About The Pull Request
moves all implementations (im aware of) for "Im a parent type dont spawn
me please" to the datum layer to standardized behavior
adds a standerized proc for filtering out "bad" items that we dont want
spawning. applies to it the subtype vendor, gifts, and a new spawner and
mystery box for a random gun (neither playerfacing)
"port" of https://github.com/shiptest-ss13/Shiptest/pull/4621



https://github.com/user-attachments/assets/22f6f0b2-b44e-411a-b3dc-6b97dc0287aa

small warning: I dont have EVERY abstract type defined right now but,
ive done a good enough job for now. Im tired of data entry rn
## Why It's Good For The Game
standardizing behavior. Might be a micro hit to performance however

having this lets us not rely on icon state to determine whether
something is a parent type and makes it much easier to tell something is
a parent type (could be applied further to things like admin spawning
menus and things like that).

need feedback on if this is actually good for the game.
## Changelog
🆑
add: Soda cans show up in the silver slime drink table.
add: Examine tag for items that are not mean to show up ingame.
refactor: Standardizes how gifts rule out abstract types.
fix: gifts no longer check if something has an inhand, massively
expanding the list of potential items.
/🆑

code/modules/antagonists/_common/antag_spawner.dm

@@ -1,4 +1,5 @@
 /obj/item/antag_spawner
+	abstract_type = /obj/item/antag_spawner
 	throw_speed = 1
 	throw_range = 5
 	w_class = WEIGHT_CLASS_TINY

code/modules/antagonists/abductor/equipment/gear/abductor_items.dm

@@ -2,6 +2,7 @@
 	icon = 'icons/obj/antags/abductor.dmi'
 	lefthand_file = 'icons/mob/inhands/antag/abductor_lefthand.dmi'
 	righthand_file = 'icons/mob/inhands/antag/abductor_righthand.dmi'
+	abstract_type = /obj/item/abductor
 
 /obj/item/proc/AbductorCheck(mob/user)
 	if (HAS_TRAIT(user, TRAIT_ABDUCTOR_TRAINING))

code/modules/antagonists/changeling/changeling_power.dm

@@ -3,6 +3,7 @@
  */
 
 /datum/action/changeling
+	abstract_type = /datum/action/changeling
 	name = "Prototype Sting - Debug button, ahelp this"
 	background_icon_state = "bg_changeling"
 	overlay_icon_state = "bg_changeling_border"

code/modules/antagonists/changeling/powers/mutations.dm

@@ -11,6 +11,7 @@
 
 //Parent to shields and blades because muh copypasted code.
 /datum/action/changeling/weapon
+	abstract_type = /datum/action/changeling/weapon
 	name = "Organic Weapon"
 	desc = "Go tell a coder if you see this"
 	helptext = "Yell at Miauw and/or Perakp"
@@ -87,6 +88,7 @@
 
 //Parent to space suits and armor.
 /datum/action/changeling/suit
+	abstract_type = /datum/action/changeling/suit
 	name = "Organic Suit"
 	desc = "Go tell a coder if you see this"
 	helptext = "Yell at Miauw and/or Perakp"

code/modules/antagonists/changeling/powers/transform.dm

@@ -9,6 +9,7 @@
 
 /obj/item/clothing/glasses/changeling
 	name = "flesh"
+	spawn_blacklisted = TRUE
 	item_flags = DROPDEL
 
 //ATTACK HAND IGNORING PARENT RETURN VALUE
@@ -24,6 +25,7 @@
 
 /obj/item/clothing/under/changeling
 	name = "flesh"
+	spawn_blacklisted = TRUE
 	item_flags = DROPDEL
 
 //ATTACK HAND IGNORING PARENT RETURN VALUE
@@ -39,6 +41,7 @@
 
 /obj/item/clothing/suit/changeling
 	name = "flesh"
+	spawn_blacklisted = TRUE
 	allowed = list(/obj/item/changeling)
 	item_flags = DROPDEL
 
@@ -56,6 +59,7 @@
 /obj/item/clothing/head/changeling
 	name = "flesh"
 	icon_state = null
+	spawn_blacklisted = TRUE
 	item_flags = DROPDEL
 
 //ATTACK HAND IGNORING PARENT RETURN VALUE
@@ -71,6 +75,7 @@
 
 /obj/item/clothing/shoes/changeling
 	name = "flesh"
+	spawn_blacklisted = TRUE
 	item_flags = DROPDEL
 
 //ATTACK HAND IGNORING PARENT RETURN VALUE
@@ -86,6 +91,7 @@
 
 /obj/item/clothing/gloves/changeling
 	name = "flesh"
+	spawn_blacklisted = TRUE
 	item_flags = DROPDEL
 
 //ATTACK HAND IGNORING PARENT RETURN VALUE
@@ -101,6 +107,7 @@
 
 /obj/item/clothing/mask/changeling
 	name = "flesh"
+	spawn_blacklisted = TRUE
 	item_flags = DROPDEL
 
 //ATTACK HAND IGNORING PARENT RETURN VALUE
@@ -116,6 +123,7 @@
 
 /obj/item/changeling
 	name = "flesh"
+	spawn_blacklisted = TRUE
 	slot_flags = ALL
 	item_flags = DROPDEL