rename checkoutCreate to createCart and remove Shopify checkout API

Signed-off-by: Loan Laux <loan@outgrow.io>

framework/reactioncommerce/utils/mutations/create-cart.ts

@@ -0,0 +1,24 @@
+import {
+  cartPayloadFragment,
+  incorrectPriceFailureDetailsFragment,
+  minOrderQuantityFailureDetailsFragment,
+} from '@framework/utils/queries/get-checkout-query'
+
+const createCartMutation = /* GraphQL */ `
+  mutation createCartMutation($input: CreateCartInput!) {
+    createCart(input: $input) {
+      cart {
+        ${cartPayloadFragment}
+      }
+      incorrectPriceFailures {
+        ${incorrectPriceFailureDetailsFragment}
+      }
+      minOrderQuantityFailures {
+        ${minOrderQuantityFailureDetailsFragment}
+      }
+      clientMutationId
+      token
+    }
+  }
+`
+export default createCartMutation