Added support for changing Line Items' order on Carts

You can now change the order of Line Items in a Cart. This enhancement helps Customers identify which Line Items belong together. Previously, the order of Line Items in a Cart was based on the sequence in which the Line Items were added to the Cart.

Changes:

• [API] Added changeLineItemsOrder update action to the Carts and My Carts APIs.
• [GraphQL API] Added ChangeCartLineItemsOrder type to the GraphQL schema.
• [GraphQL API] Added changeLineItemsOrder input field to the CartUpdateAction type.

We made the following addition to the GraphQL SDL:

extend input CartUpdateAction {
  changeLineItemsOrder: ChangeCartLineItemsOrder
}

input ChangeCartLineItemsOrder {
  lineItemOrder: String!
}