Added "s" alias to SpawnCommand (closes #1840)

src/main/java/emu/grasscutter/command/commands/SpawnCommand.java

@@ -25,7 +25,7 @@ import static emu.grasscutter.utils.Language.translate;
 
 @Command(
     label = "spawn",
-    aliases = {"drop"},
+    aliases = {"drop", "s"},
     usage = {
         "<itemId> [x<amount>] [blk<blockId>] [grp<groupId>] [cfg<configId>] <x> <y> <z>",
         "<gadgetId> [x<amount>] [state<state>] [maxhp<maxhp>] [hp<hp>(0 for infinite)] [atk<atk>] [def<def>] [blk<blockId>] [grp<groupId>] [cfg<configId>] <x> <y> <z>",