Adds Sleep Music to Surgery/Cryo/Sleeper

Plays quiet music when you have;
- An anesthetic mask on your face.
- Been put into a cryopod
- Been put into a sleeper

TBD: Maybe make sleeping do it, but iirc even dying does sleep.

There is a pref toggle for these under Preferences: "Sleeping Music"

Example [here](https://streamable.com/pls63y) of surgery being done. Volume is higher than normal, was adjusted down to 40%.

modular_chomp/code/modules/mob/living/carbon/carbon.dm

@@ -0,0 +1,12 @@
+/mob/living/carbon
+	var/datum/looping_sound/mob/cozyloop/cozyloop
+
+/mob/living/carbon/Initialize()
+	. = ..()
+
+	cozyloop = new(list(src), FALSE)
+
+/mob/living/carbon/Destroy()
+	. = ..()
+
+	QDEL_NULL(cozyloop)