Add toggle for farting noises

Add farting noises to Citadel toggles
Add channel for farting noises
Integrate fart sound effects into /proc/get_sfx
Use similar pattern to vore noises

modular_citadel/code/modules/client/preferences.dm

@@ -21,6 +21,7 @@
 	//vore prefs
 	var/toggleeatingnoise = TRUE
 	var/toggledigestionnoise = TRUE
+	var/togglefartingnoise = TRUE
 	var/hound_sleeper = TRUE
 	var/cit_toggles = TOGGLES_CITADEL