Fixed:: Issues in the process of booking creation from back office

[sumitwebkul]

Fixed below issues:

• Getting a fatal error when removing the product from the cart from a different tab before creating an order.
• Getting exceptions during payment when removing all rooms from the cart just before payment from a different tab.
• Getting fatal error on book now page if back date order for super admin is disabled
• When clicking on the "add new" button from the order list page, should redirect to the book now page.