Restaurant point-of-sale order lines now store note and preparation skip information in the database, matching what staff already use in the front end. This prevents errors in related Point of Sale and IoT workflows and improves reliability for restaurant operations.

The note and mp_skip field of pos.order.line only exist in the front-end
application, this causes errors in some task of the PoS and IoT teams.

This pr adds the fields to the database, resolving these problems.