Refactor code structure and remove redundant sections for improved readability and maintainability

ui/main_menu/main_menu.gd

@@ -0,0 +1,11 @@
+extends VBoxContainer
+
+
+# Called when the node enters the scene tree for the first time.
+func _ready() -> void:
+    pass # Replace with function body.
+
+
+# Called every frame. 'delta' is the elapsed time since the previous frame.
+func _process(delta: float) -> void:
+    pass