Adds a user type to integrated circuits, refactors the list pick component. (#79412)

## About The Pull Request
Added a user type to integrated circuits that can't be stored as a user
type but can be typecasted to entity. Useful for components that
directly ask for an input from the user, like the list pick component.

Refactored the list pick component to use this user port and to also
send failure signals whenever a success signal is not sent.
Removed the triggered port for the list pick component.

Also fixes a runtime that occurs with the list pick component if the
list passed in only contains null values.

## Why It's Good For The Game
Can't force a prompt onto people who haven't interacted with your
circuit.

## Changelog
🆑
add: Added a user type to integrated circuits
/🆑

---------

Co-authored-by: Watermelon914 <3052169-Watermelon914@users.noreply.gitlab.com>

code/modules/tgui_input/list.dm

@@ -29,6 +29,9 @@
 	if(!user.client.prefs.read_preference(/datum/preference/toggle/tgui_input))
 		return input(user, message, title, default) as null|anything in items
 	var/datum/tgui_list_input/input = new(user, message, title, items, default, timeout, ui_state)
+	if(input.invalid)
+		qdel(input)
+		return
 	input.ui_interact(user)
 	input.wait()
 	if (input)
@@ -62,6 +65,8 @@
 	var/closed
 	/// The TGUI UI state that will be returned in ui_state(). Default: always_state
 	var/datum/ui_state/state
+	/// Whether the tgui list input is invalid or not (i.e. due to all list entries being null)
+	var/invalid = FALSE
 
 /datum/tgui_list_input/New(mob/user, message, title, list/items, default, timeout, ui_state)
 	src.title = title
@@ -81,6 +86,9 @@
 		string_key = avoid_assoc_duplicate_keys(string_key, repeat_items)
 		src.items += string_key
 		src.items_map[string_key] = i
+
+	if(length(src.items) == 0)
+		invalid = TRUE
 	if (timeout)
 		src.timeout = timeout
 		start_time = world.time