add /prestiges

also fix inconsistency with checking groups

src/main/java/sh/okx/rankup/commands/RankupCommand.java

@@ -1,5 +1,6 @@
 package sh.okx.rankup.commands;
 
+import lombok.RequiredArgsConstructor;
 import org.bukkit.command.Command;
 import org.bukkit.command.CommandExecutor;
 import org.bukkit.command.CommandSender;
@@ -14,17 +15,13 @@ import sh.okx.rankup.ranks.Rankups;
 import java.util.Map;
 import java.util.WeakHashMap;
 
+@RequiredArgsConstructor
 public class RankupCommand implements CommandExecutor {
   // weak hash maps so players going offline are automatically removed.
   // otherwise there is a potential (but small) memory leak.
   private final Map<Player, Long> confirming = new WeakHashMap<>();
-
   private final Rankup plugin;
 
-  public RankupCommand(Rankup plugin) {
-    this.plugin = plugin;
-  }
-
   @Override
   public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
     // check if player