Add beach towels. (#31667)

* Add beach towels.

* Add basic towel. Attempt absorbency. Add towel names.

* Make towels pick up and spread blood.
Move towel place-on-floor function to beach towels.

* Move amount to base cleanable. Refine towel procs.

* Ensure towel picks up blood.

* Add species sprites and inhands.

* Apply suggestions from code review.

* Fix ussp space ruin.

* Whitespace.

* Prevent picking up blood DNA already on the towel from mobs/items without decal amounts.

code/modules/reagents/chemistry/reagents/drinks_reagents.dm

@@ -1137,8 +1137,8 @@
 	var/drop_type = /obj/effect/decal/cleanable/reagent/drip
 	var/obj/effect/decal/cleanable/reagent/drip/drop = locate() in T
 	if(drop)
-		if(drop.amount < 5)
-			drop.amount++
+		if(drop.cleanable_amount < 5)
+			drop.cleanable_amount++
 			var/image/I = image(drop.icon, drop.random_icon_states)
 			I.icon += drop.basecolor
 			drop.overlays |= I