/tg/ pref datums (part 1) (#16219)

* TG Prefs (Step 1: JSON savefiles)

* TG Prefs (Step 2: Preference Datum Code)

* TG Prefs (Step 3: Convert /datum/client_preferences)

* TG Prefs (Step 4: Clean up and finishing touches)

* Fix some weird compile errors from the rebase

code/controllers/subsystems/ping.dm

@@ -27,7 +27,7 @@ SUBSYSTEM_DEF(ping)
 		var/client/client = currentrun[currentrun.len]
 		currentrun.len--
 
-		if(!client?.is_preference_enabled(/datum/client_preference/vchat_enable))
+		if(!client?.prefs?.read_preference(/datum/preference/toggle/vchat_enable))
 			winset(client, "output", "on-show=&is-disabled=0&is-visible=1")
 			winset(client, "browseroutput", "is-disabled=1;is-visible=0")
 			client.tgui_panel.oldchat = TRUE