Part of: WOOMOB-1508

Description

• Adds loadBooking(bookingID:, siteID:) remote method for loading a single booking
• Adds loadOrders(for siteID:, orderIDs:) remote method to load a set of orders with specified IDs.
• Adds synchronizeBooking action that fetches both booking and the corresponding order.
• Augments synchronizeBookings action to also download related orders using the loadOrders(for siteID:, orderIDs:).
• Adds new tests and update existing.

Note: The new Booking related models containing product, customer and order info aren't yet applied. This will be handled in a separate PR depending on the Bookings: Add new entities for booking info.

Testing steps

• Use CIAB site with existing bookings.
• Use Proxyman
• Navigate to the Booking list
• In Proxyman make sure the orders are fetched (est_route=/wc/v3/orders) for each non-empty bookings response (rest_route=/wc-bookings/v2/bookings) containing actual bookings.
• In Proxyman make sure the corresponding wc/v3/orders requests contain the include argument with non-repeating order ids. Make sure the corresponding orders returned in the response.
• Make sure the returned orders are logged into the Xcode debug console by: print("The order for the booking \(readOnlyBooking.bookingID): \(associatedOrder)")

Testing information

Tested in iOS 26 (iPhone 17) Simulator.

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.