[MIRROR] Invisibility refactor [MDB IGNORE] (#24405)

* Invisibility refactor (#78908)

This adds a tracker for sources of invisibility and a priority system. I
needed this for another thing so I'm doing this first since it touches a
lot of code. As for the bugs fixed in the changelog, it's only what I
noticed while going through everything and there's likely a few more
things fixed with this. This should be testmerged for a while, I'll
bring this out of draft when it feels safe.

🆑
admin: Invisimin can now be used on mobs that are already invisible,
whether through temporary or permanent effects.
fix: Monkeyize/Humanize mob transformations no longer permanently reveal
invisible mobs if they had effects making them invisible otherwise.
fix: Objects with the undertile element that have been made invisible
through other means are no longer revealed by being uncovered.
/🆑

* Invisibility refactor

---------

Co-authored-by: Emmett Gaines <ninjanomnom@gmail.com>

code/modules/mining/lavaland/megafauna_loot.dm

@@ -651,7 +651,7 @@
 
 /obj/item/melee/ghost_sword/Destroy()
 	for(var/mob/dead/observer/G in spirits)
-		G.invisibility = GLOB.observer_default_invisibility
+		G.RemoveInvisibility(type)
 	spirits.Cut()
 	STOP_PROCESSING(SSobj, src)
 	. = ..()
@@ -690,10 +690,10 @@
 			continue
 		var/mob/dead/observer/G = i
 		ghost_counter++
-		G.invisibility = 0
+		G.SetInvisibility(INVISIBILITY_NONE, id=type, priority=INVISIBILITY_PRIORITY_BASIC_ANTI_INVISIBILITY)
 		current_spirits |= G
 	for(var/mob/dead/observer/G in spirits - current_spirits)
-		G.invisibility = GLOB.observer_default_invisibility
+		G.RemoveInvisibility(type)
 	spirits = current_spirits
 	return ghost_counter
 

code/modules/mining/lavaland/tendril_loot.dm

@@ -1052,7 +1052,7 @@
 
 /obj/item/cursed_katana/proc/cloak(mob/living/target, mob/user)
 	user.alpha = 150
-	user.invisibility = INVISIBILITY_OBSERVER // so hostile mobs cant see us or target us
+	user.SetInvisibility(INVISIBILITY_OBSERVER, id=type) // so hostile mobs cant see us or target us
 	user.add_sight(SEE_SELF) // so we can see us
 	user.visible_message(span_warning("[user] vanishes into thin air!"),
 		span_notice("You enter the dark cloak."))
@@ -1066,7 +1066,7 @@
 
 /obj/item/cursed_katana/proc/uncloak(mob/user)
 	user.alpha = 255
-	user.invisibility = 0
+	user.RemoveInvisibility(type)
 	user.clear_sight(SEE_SELF)
 	user.visible_message(span_warning("[user] appears from thin air!"),
 		span_notice("You exit the dark cloak."))