Add method to retrieve UPS Shipment status in shipping method plugin

Currently, there is no direct method available in the UPS plugin to retrieve the status of UPS shipments programmatically. This functionality is essential for scenarios where custom code needs to interact with UPS shipments, such as updating the state of an order or shipment based on UPS tracking information.

API documentation: https://developer.ups.com/api/reference?loc=en_US#operation/getSingleTra...

Example code demonstrating how it could be used:

        // Instantiate the UPS shipment method plugin.
        $ups_plugin = $shipment->getShippingMethod()->getPlugin();

        $result = $ups_plugin->trackShipment($shipment);
        ...