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/game/objects/structures/construction_console/construction_actions.dm

@@ -67,7 +67,11 @@
 	if(..())
 		return
 	var/list/buildlist = list("Walls and Floors" = RCD_FLOORWALL, "Airlocks" = RCD_AIRLOCK, "Deconstruction" = RCD_DECONSTRUCT, "Windows and Grilles" = RCD_WINDOWGRILLE)
-	var/buildmode = input(owner, "Set construction mode.", "Base Console", null) in buildlist
+	var/buildmode = tgui_input_list(owner, "Set construction mode", "Base Console", buildlist)
+	if(isnull(buildmode))
+		return
+	if(isnull(buildlist[buildmode]))
+		return
 	check_rcd()
 	base_console.internal_rcd.construction_mode = buildlist[buildmode]
 	to_chat(owner, "Build mode is now [buildmode].")