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%.

code/modules/client/preference_setup/global/setting_datums.dm

@@ -381,7 +381,7 @@ var/list/_client_preferences_by_type
 	key = "RECEIVE_TIPS"
 	enabled_description = "Enabled"
 	disabled_description = "Disabled"
- 
+
 /datum/client_preference/pain_frequency
 	description = "Pain Messages Cooldown"
 	key = "PAIN_FREQUENCY"
@@ -389,6 +389,14 @@ var/list/_client_preferences_by_type
 	enabled_description = "Extended"
 	disabled_description = "Default"
 
+// CHOMPAdd
+/datum/client_preference/sleep_music
+	description = "Sleeping Music"
+	key = "SLEEP_MUSIC"
+	enabled_description = "Audible"
+	disabled_description = "Silent"
+// CHOMPAdd End
+
 
 /********************
 * Staff Preferences *

code/modules/client/preferences_ch.dm

@@ -12,3 +12,18 @@
 	SScharacter_setup.queue_preferences_save(prefs)
 
 	feedback_add_details("admin_verb","TAlarmLoops") //If you are copy-pasting this, ensure the 2nd parameter is unique to the new proc!
+
+/client/verb/toggle_sleep_music()
+	set name = "Toggle Sleeping Music"
+	set category = "Preferences"
+	set desc = "When enabled, you will hear cozy music played during surgery, cryo, and sleeper pod usage."
+
+	var/pref_path = /datum/client_preference/sleep_music
+
+	toggle_preference(pref_path)
+
+	to_chat(src, "You are [ (is_preference_enabled(pref_path)) ? "now" : "no longer"] hearing sleeping music while in cryo/surgery/sleeper.")
+
+	SScharacter_setup.queue_preferences_save(prefs)
+
+	feedback_add_details("admin_verb", "TSleepMusic")