Add main menu scene and script for Godot 4 project validation

scripts/main_menu.gd

@@ -0,0 +1,13 @@
+extends Control
+
+
+func _ready():
+	pass
+
+
+func _on_play_button_pressed():
+	get_tree().change_scene_to_file("res://scenes/game.tscn")
+
+
+func _on_quit_button_pressed():
+	get_tree().quit()