Refactored the abstract meta propriety (#19797)

Refactored the abstract meta propriety into defines.
It's now more easy to spot/see abstract types thanks to the macro that
defines them.
Added a check on initialization of atoms to avoid spawning abstract
types.
Made the spawn_atom proc check for abstractness.
Made the spawn_atom proc use tgui_list for types list shorter than 1000
elements, which enables to search in them. It's too laggy on larger
lists so above 1000 it uses the builtin input.
Made the spawn_atom use a list subtraction instead of a double list,
it's lighter on memory and processing.

code/modules/admin/admin.dm

@@ -1016,27 +1016,36 @@ var/global/enabled_spooking = 0
 	set desc = "(atom path) Spawn an atom"
 	set name = "Spawn"
 
-	if(!check_rights(R_SPAWN))	return
+	if(!check_rights(R_SPAWN))
+		return
 
-	var/list/types = typesof(/atom)
-	var/list/matches = new()
+	var/list/matches = typesof(/atom)
 
-	for(var/path in types)
-		if(findtext("[path]", object))
-			matches += path
+	for(var/path in matches)
+		if(!findtext("[path]", object))
+			matches -= path
 
-	if(matches.len==0)
+	if(!length(matches))
 		return
 
 	var/chosen
-	if(matches.len==1)
+	if(length(matches) == 1)
 		chosen = matches[1]
 	else
-		chosen = input("Select an atom type", "Spawn Atom", matches[1]) as null|anything in matches
+		//TGUI input gets fucky if the list is too large, so we revert back to standard input in that case
+		if(length(matches) < 1000)
+			chosen = tgui_input_list(usr, "Select an atom type", "Spawn Atom", matches)
+		else
+			chosen = input("Select an atom type", "Spawn Atom", matches[1]) as null|anything in matches
+
 		if(!chosen)
 			return
 
-	if(ispath(chosen,/turf))
+	if(is_abstract(chosen))
+		tgui_alert(usr, "This is an abstract type, you can't spawn it!", "Abstract Type")
+		return
+
+	if(ispath(chosen, /turf))
 		var/turf/T = get_turf(usr.loc)
 		T.ChangeTurf(chosen)
 	else