Revert "Merge pull request #16240 from ShadowLarkens/revert"

This reverts commit 885171f985, reversing
changes made to 3e314f8064.

code/modules/client/preferences/middleware/_middleware.dm

@@ -0,0 +1,52 @@
+/// Preference middleware is code that helps to decentralize complicated preference features.
+/datum/preference_middleware
+	/// The preferences datum
+	var/datum/preferences/preferences
+
+	/// The key that will be used for get_constant_data().
+	/// If null, will use the typepath minus /datum/preference_middleware.
+	var/key = null
+
+	/// Map of ui_act actions -> proc paths to call.
+	/// Signature is `(list/params, mob/user) -> TRUE/FALSE.
+	/// Return output is the same as ui_act--TRUE if it should update, FALSE if it should not
+	var/list/action_delegations = list()
+
+/datum/preference_middleware/New(datum/preferences)
+	src.preferences = preferences
+
+	if (isnull(key))
+		// + 2 coming from the off-by-one of copytext, and then another from the slash
+		key = copytext("[type]", length("[parent_type]") + 2)
+
+/datum/preference_middleware/Destroy()
+	preferences = null
+	return ..()
+
+/// Append all of these into ui_data
+/datum/preference_middleware/proc/get_ui_data(mob/user)
+	return list()
+
+/// Append all of these into ui_static_data
+/datum/preference_middleware/proc/get_ui_static_data(mob/user)
+	return list()
+
+/// Append all of these into ui_assets
+/datum/preference_middleware/proc/get_ui_assets()
+	return list()
+
+/// Append all of these into /datum/asset/json/preferences.
+/datum/preference_middleware/proc/get_constant_data()
+	return null
+
+/// Merge this into the result of compile_character_preferences.
+/datum/preference_middleware/proc/get_character_preferences(mob/user)
+	return null
+
+/// Called every set_preference, returns TRUE if this handled it.
+/datum/preference_middleware/proc/pre_set_preference(mob/user, preference, value)
+	return FALSE
+
+/// Called when a character is changed.
+/datum/preference_middleware/proc/on_new_character(mob/user)
+	return