Upgrade Paper to 1.21, use Brigadier command system

src/main/java/de/shiewk/smoderation/paper/command/CommandProvider.java

@@ -0,0 +1,19 @@
+package de.shiewk.smoderation.paper.command;
+
+import com.mojang.brigadier.tree.LiteralCommandNode;
+import io.papermc.paper.command.brigadier.CommandSourceStack;
+
+import java.util.Collection;
+import java.util.List;
+
+public interface CommandProvider {
+
+    LiteralCommandNode<CommandSourceStack> getCommandNode();
+
+    String getCommandDescription();
+
+    default Collection<String> getAliases(){
+        return List.of();
+    }
+
+}