Add frontend_viewable checkbox to admin new order form

[Lindau2]

Replaced the hard-coded frontend_viewable value in the admin order creation flow with a dynamic implementation based on user input.

Updated the orders controller to read the frontend_viewable value from request parameters instead of always defaulting to false.

Introduced a new admin order creation view to allow input before order creation, including a checkbox that lets admins control whether an order is visible to the customer.

Modified the new action to handle both rendering the form and creating the order on submission, instead of immediately creating and redirecting.

[jarednorman]

I don't even think that controller change is syntactically valid.