Rewrite commands

Signed-off-by: Jaida Wu <mlgmxyysd@meowcat.org>

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

@@ -0,0 +1,23 @@
+package emu.grasscutter.command.commands;
+
+import emu.grasscutter.Grasscutter;
+import emu.grasscutter.command.Command;
+import emu.grasscutter.command.CommandHandler;
+import emu.grasscutter.game.GenshinPlayer;
+
+import java.util.List;
+
+@Command(label = "stop", usage = "stop",
+        description = "Stops the server", permission = "server.stop")
+public class Stop implements CommandHandler {
+
+    @Override
+    public void onCommand(GenshinPlayer sender, List<String> args) {
+        CommandHandler.sendMessage(null, "Server shutting down...");
+        for (GenshinPlayer p : Grasscutter.getGameServer().getPlayers().values()) {
+            CommandHandler.sendMessage(p, "Server shutting down...");
+        }
+
+        System.exit(1);
+    }
+}