Added new state 'Delivered' to Order ShipmentState

With the new ShipmentState, Delivered, you can now track the orders that are received by the customer.

Previously, this was only possible by using a custom state on the Order, or on the Line Item if they have more shipments per Order.

Changes:

• [API] Added state Delivered to ShipmentState
• [GraphQL API] Changed the ShipmentState type:
  • Enum value Delivered was added to enum ShipmentState

The following changes were introduced in terms of GraphQL SDL:

extend enum ShipmentState {
  Delivered
}