Added Cart replication to My Carts

Creating a new Cart by replicating an existing Cart or Order can be useful in case a Customer wants to cancel a recent order to make some changes, or if a previous order should be ordered again. This has been supported for Carts already, and now we added a replicatiion endpoint for My Carts also.

Changes:

• [API] Added Replicate My Cart endpoint.
• [API] Added ReplicaMyCartDraft.
• [GraphQL API] Changed the Mutation type:
  • Added the replicateMyCart field to the Mutation type.

Introduced the following changes to the GraphQL schema (in SDL format):

extend type Mutation {
  replicateMyCart(reference: ReferenceInput!): Cart
}