feat(workflows-sdk,core-flows,medusa,types): add workflow to update promotions to cart (#6474)

what:

- adds API + workflow to add/remove promotions in a cart
- minor fixes in promotions module
- minor type fixes in cart module
- typing fix in workflows-sdk (Thanks @adrien2p)
- fix step result in workflows-sdk (Thanks @adrien2p)

RESOLVES CORE-1768

Co-authored-by: Adrien de Peretti <25098370+adrien2p@users.noreply.github.com>

packages/cart/integration-tests/__tests__/services/cart-module/index.spec.ts

@@ -291,12 +291,9 @@ describe("Cart Module Service", () => {
         },
       ])
 
-      const updatedCart = await service.update(
-        createdCart.id,
-        {
-          email: "test@email.com",
-        }
-      )
+      const updatedCart = await service.update(createdCart.id, {
+        email: "test@email.com",
+      })
 
       const [cart] = await service.list({ id: [createdCart.id] })