Updated /shippingOptions endpoint

Added a new array estimatedShippingTimeAtCheckoutSettings which contains information about the settings of the estimated shipping time shown at checkout.

The array consists of 5 fields: estimatedDeliveryDateAtCheckoutEnabled, estimatedTransitTimeInDays, fulfillmentTimeInDays, shippingBusinessDays, cutoffTimeForSameDayPacking, and it's available via these requests: