add main menu and scene manager

core/main_menu/main_menu.gd

@@ -0,0 +1,10 @@
+extends Control
+
+@onready var settings_menu: Control = $%SettingsMenu
+
+func _on_play_button_on_button_pressed() -> void:
+	SceneManager.change_scene(SceneConfig.SceneName.GAME)
+
+
+func _on_settings_button_on_button_pressed() -> void:
+	$%SettingsMenu.visible = !$%SettingsMenu.visible