TGUI list conversions + bug fixes (#63354)

About The Pull Request

    Converts more inputs to TGUI. Possibly all user-facing input lists in the game.
    Did any surrounding text/number inputs as well
    Added null choice support so users can press cancel.
    Added some misc TGUI input fixes
    Fixed custom vendors while I was there

I refactored a lot of code while just poking around.
Primarily, usage of .len in files where I was already working on lists.
Some code was just awful - look at guardian.dm and its non use of early returns
If there are any disputes, I can revert it just fine, those changes are not integral to the PR.
Why It's Good For The Game

Fixes #63629
Fixes #63307
Fixes custom vendors /again/
Text input is more performant.
Part of a long series of TGUI conversion to make the game more visually appealing
Changelog

cl
refactor: The majority of user facing input lists have been converted to TGUI.
refactor: Tgui text inputs now scale with entered input.
fix: Many inputs now properly accept cancelling out of the menu.
fix: Fixes an edge case where users could not press enter on number inputs.
fix: Custom vendor bluescreen.
fix: You can now press ENTER on text inputs without an entry to cancel.
/cl

code/modules/admin/smites/imaginary_friend_special.dm

@@ -14,7 +14,9 @@
 	var/random_appearance
 
 /datum/smite/custom_imaginary_friend/configure(client/user)
-	friend_candidate_client = tgui_input_list(user, "Pick the player to put in control.", "New Imaginary Friend", sort_list(GLOB.clients))
+	friend_candidate_client = tgui_input_list(user, "Pick the player to put in control", "New Imaginary Friend", sort_list(GLOB.clients))
+	if(isnull(friend_candidate_client))
+		return
 
 	if(QDELETED(friend_candidate_client))
 		to_chat(user, span_notice("Selected player no longer has a client, aborting."))