Add a DISABLE_DREAMLUAU define, for disabling dreamluau at compile-time (#89359)

## About The Pull Request

this adds a new define, `DISABLE_DREAMLUAU` (commented out by default),
which does... exactly what it says on the tin. it fully disables any
dreamluau-related code (the "Open Lua Editor" admin verb is left in,
albeit just giving the user a warning saying Lua is disabled, just so
there's no confusion about the verb itself being missing)

when compiling with OpenDream outside of CI (so dreamluau code will
still be linted), `DISABLE_DREAMLUAU` will be defined by default, tho.

## Why It's Good For The Game

makes OpenDream testing easier

## Changelog

no user-facing changes. or even code changes for most cases.

code/modules/error_handler/error_handler.dm

@@ -103,12 +103,14 @@ GLOBAL_VAR_INIT(total_runtimes_skipped, 0)
 	// The proceeding mess will almost definitely break if error messages are ever changed
 	var/list/splitlines = splittext(E.desc, "\n")
 	var/list/desclines = list()
+#ifndef DISABLE_DREAMLUAU
 	var/list/state_stack = GLOB.lua_state_stack
 	var/is_lua_call = length(state_stack)
 	var/list/lua_stacks = list()
 	if(is_lua_call)
 		for(var/level in 1 to state_stack.len)
 			lua_stacks += list(splittext(DREAMLUAU_GET_TRACEBACK(level), "\n"))
+#endif
 	if(LAZYLEN(splitlines) > ERROR_USEFUL_LEN) // If there aren't at least three lines, there's no info
 		for(var/line in splitlines)
 			if(LAZYLEN(line) < 3 || findtext(line, "source file:") || findtext(line, "usr.loc:"))
@@ -124,8 +126,10 @@ GLOBAL_VAR_INIT(total_runtimes_skipped, 0)
 				desclines += line
 	if(usrinfo) //If this info isn't null, it hasn't been added yet
 		desclines.Add(usrinfo)
+#ifndef DISABLE_DREAMLUAU
 	if(is_lua_call)
 		SSlua.log_involved_runtime(E, desclines, lua_stacks)
+#endif
 	if(silencing)
 		desclines += "  (This error will now be silenced for [DisplayTimeText(configured_error_silence_time)])"
 	if(GLOB.error_cache)