Create player creation event & move join event to player

src/main/java/emu/grasscutter/server/event/game/PlayerCreationEvent.java

@@ -0,0 +1,27 @@
+package emu.grasscutter.server.event.game;
+
+import emu.grasscutter.game.player.Player;
+import emu.grasscutter.server.event.types.GameEvent;
+import emu.grasscutter.server.game.GameSession;
+
+public final class PlayerCreationEvent extends GameEvent {
+    private final GameSession session;
+    private Class<? extends Player> playerClass;
+    
+    public PlayerCreationEvent(GameSession session, Class<? extends Player> playerClass) {
+        this.session = session;
+        this.playerClass = playerClass;
+    }
+    
+    public GameSession getSession() {
+        return this.session;
+    }
+    
+    public void setPlayerClass(Class<? extends Player> playerClass) {
+        this.playerClass = playerClass;
+    }
+    
+    public Class<? extends Player> getPlayerClass() {
+        return this.playerClass;
+    }
+}