refactor: make listeners an interface

(except the one in Bot, which extends MCProtocolLib's SessionAdaptor, not sure how exactly make them complement)

src/main/java/me/chayapak1/chomens_bot/plugins/PositionPlugin.java

@@ -21,7 +21,7 @@ import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
 // some part of the code used to be in a test plugin but i thought it would be useful in the future so i moved it here
-public class PositionPlugin extends Bot.Listener {
+public class PositionPlugin extends Bot.Listener implements TickPlugin.Listener {
     private final Bot bot;
 
     private final List<Listener> listeners = new ArrayList<>();
@@ -37,8 +37,6 @@ public class PositionPlugin extends Bot.Listener {
     public PositionPlugin (Bot bot) {
         this.bot = bot;
 
-        bot.addListener(this);
-
         // notchian clients also does this, sends the position packet every second
         bot.executor.scheduleAtFixedRate(() -> {
             if (!bot.loggedIn || isGoingDownFromHeightLimit) return;
@@ -52,12 +50,13 @@ public class PositionPlugin extends Bot.Listener {
             ));
         }, 0, 1, TimeUnit.SECONDS);
 
-        bot.tick.addListener(new TickPlugin.Listener() {
-            @Override
-            public void onTick() {
-                handleHeightLimit();
-            }
-        });
+        bot.addListener(this);
+        bot.tick.addListener(this);
+    }
+
+    @Override
+    public void onTick() {
+        handleHeightLimit();
     }
 
     @Override
@@ -267,8 +266,8 @@ public class PositionPlugin extends Bot.Listener {
     public void addListener (Listener listener) { listeners.add(listener); }
 
     @SuppressWarnings("unused")
-    public static class Listener {
-        public void positionChange (Vector3d position) {}
-        public void playerMoved (PlayerEntry player, Vector3d position, Rotation rotation) {}
+    public interface Listener {
+        default void positionChange (Vector3d position) {}
+        default void playerMoved (PlayerEntry player, Vector3d position, Rotation rotation) {}
     }
 }