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/game/objects/effects/spawners/random/weapon.dm

@@ -0,0 +1,10 @@
+/obj/effect/spawner/random/weapon
+	icon_state = "laser_gun"
+
+/obj/effect/spawner/random/weapon/full_gun
+	loot_subtype_path = /obj/item/gun
+
+/obj/effect/spawner/random/weapon/full_gun/make_item(spawn_loc, type_path_to_make)
+	var/obj/item/gun/spawned_gun = new type_path_to_make(spawn_loc)
+	spawned_gun.unlock()
+	return spawned_gun