Converts the crackable element to mutable appearances, saves 0.15 seconds of init (#73941)

## About The Pull Request

Instead of passing in an icon as a source to the alpha mask filter, we
can stick a mutable appearance in our overlays list with a render target
set, and use that render target to do our masking. Remember to use "*"
to avoid rendering the crack twice

## Why It's Good For The Game

CPU time

code/datums/elements/crackable.dm

@@ -2,7 +2,7 @@
 /datum/element/crackable
 	element_flags = ELEMENT_BESPOKE
 	argument_hash_start_idx = 2
-	var/list/icon/crack_icons
+	var/list/mutable_appearance/crack_appearances
 	/// The level at which the object starts showing cracks, 1 being at full health and 0.5 being at half health
 	var/crack_integrity = 1
 
@@ -11,17 +11,17 @@
 	if(!isobj(target))
 		return ELEMENT_INCOMPATIBLE
 	src.crack_integrity = crack_integrity || src.crack_integrity
-	if(!crack_icons) // This is the first attachment and we need to do first time setup
-		crack_icons = list()
+	if(!crack_appearances) // This is the first attachment and we need to do first time setup
+		crack_appearances = list()
 		for(var/state in crack_states)
-			for(var/i in 1 to 36)
-				var/icon/new_crack_icon = icon(crack_icon, state)
-				new_crack_icon.Turn(i * 10)
-				crack_icons += new_crack_icon
+			for(var/i in 1 to 35)
+				var/mutable_appearance/crack = mutable_appearance(crack_icon, state)
+				crack.transform.Turn(i * 10)
+				crack_appearances += crack
 	RegisterSignal(target, COMSIG_ATOM_INTEGRITY_CHANGED, PROC_REF(IntegrityChanged))
 
 /datum/element/crackable/proc/IntegrityChanged(obj/source, old_value, new_value)
 	SIGNAL_HANDLER
 	if(new_value >= source.max_integrity * crack_integrity)
 		return
-	source.AddComponent(/datum/component/cracked, crack_icons, crack_integrity)
+	source.AddComponent(/datum/component/cracked, crack_appearances, crack_integrity)