feat(core-flows,medusa,types,utils): adds update cart API with promotions (#6514)

what:

- adds update cart API
  - workflow
  - promotions
  - sales channel
  - region
  - customer

packages/utils/src/promotion/index.ts

@@ -41,3 +41,9 @@ export enum ComputedActions {
   REMOVE_SHIPPING_METHOD_ADJUSTMENT = "removeShippingMethodAdjustment",
   CAMPAIGN_BUDGET_EXCEEDED = "campaignBudgetExceeded",
 }
+
+export enum PromotionActions {
+  ADD = "add",
+  REMOVE = "remove",
+  REPLACE = "replace",
+}