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/surgery/organs/_organ.dm

@@ -1,6 +1,7 @@
 /obj/item/organ
 	name = "organ"
 	icon = 'icons/obj/medical/organs/organs.dmi'
+	abstract_type = /obj/item/organ
 	w_class = WEIGHT_CLASS_SMALL
 	throwforce = 0
 	/// The mob that owns this organ.

code/modules/surgery/organs/internal/cyberimp/augments_arms.dm

@@ -1,6 +1,7 @@
 /obj/item/organ/cyberimp/arm
 	name = "arm-mounted implant"
 	desc = "An implant that goes in your arm to improve it."
+	abstract_type = /obj/item/organ/cyberimp/arm
 	zone = BODY_ZONE_R_ARM
 	slot = ORGAN_SLOT_RIGHT_ARM_AUG
 	w_class = WEIGHT_CLASS_SMALL

code/modules/surgery/organs/internal/cyberimp/augments_chest.dm

@@ -1,6 +1,7 @@
 /obj/item/organ/cyberimp/chest
 	name = "cybernetic torso implant"
 	desc = "Implants for the organs in your torso."
+	abstract_type = /obj/item/organ/cyberimp/chest
 	zone = BODY_ZONE_CHEST
 
 /obj/item/organ/cyberimp/chest/nutriment

code/modules/surgery/organs/internal/cyberimp/augments_internal.dm

@@ -2,7 +2,7 @@
 /obj/item/organ/cyberimp
 	name = "cybernetic implant"
 	desc = "A state-of-the-art implant that improves a baseline's functionality."
-
+	abstract_type = /obj/item/organ/cyberimp
 	organ_flags = ORGAN_ROBOTIC
 	failing_desc = "seems to be broken."
 	/// icon of the bodypart overlay we're going to be applying to our owner