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/datums/elements/surgery_initiator.dm

@@ -62,11 +62,13 @@
 					available_surgeries[surgeryloop_two.name] = surgeryloop_two
 					break
 
-		if(!available_surgeries.len)
+		if(!length(available_surgeries))
 			return
 
 		var/pick_your_surgery = tgui_input_list(user, "Which procedure?", "Surgery", sort_list(available_surgeries))
-		if(pick_your_surgery && user?.Adjacent(livingtarget) && (source in user))
+		if(isnull(pick_your_surgery))
+			return
+		if(user?.Adjacent(livingtarget) && (source in user))
 			var/datum/surgery/surgeryinstance_notonmob = available_surgeries[pick_your_surgery]
 
 			for(var/i_three in livingtarget.surgeries)