Move events

src/main/java/emu/grasscutter/server/event/types/GameEvent.java

+package emu.grasscutter.server.event.types;
+
+import emu.grasscutter.server.event.Event;
+
+/**
+ * An event that is related to the game.
+ */
+public abstract class GameEvent extends Event {
+    
+}
\ No newline at end of file

src/main/java/emu/grasscutter/server/event/ServerEvent.java → src/main/java/emu/grasscutter/server/event/types/ServerEvent.java

-package emu.grasscutter.server.event;
+package emu.grasscutter.server.event.types;
+
+import emu.grasscutter.server.event.Event;
 
 /**
  * An event that is related to the internals of the server.