Implement playable Mac client and rendering validation

script/playable_config_gate.gd

@@ -0,0 +1,14 @@
+extends SceneTree
+
+const Config = preload("res://testing/playable_config.gd")
+
+func _init() -> void:
+	var path := OS.get_environment("MT_PLAYABLE_VALIDATE_CONFIG")
+	var result := Config.load_file(path)
+	if not result.ok:
+		for error in result.errors:
+			printerr("CONFIG: " + String(error))
+		quit(2)
+		return
+	print("PLAYABLE CONFIG: PASS " + path)
+	quit(0)