This update simplifies the Point of Sale codebase by removing unused screens and small one-off interface components. It should make future maintenance and testing easier without changing the normal cashier or restaurant sales experience.

This PR cleans up miscellaneous things:
- some utility components that were used once or twice have been inlined
- the ad-hoc mecanism for shared state in pos_sale has been moved into the pos store
- some dead code has been removed (MobileOrderManagementScreen)

enterprise: https://github.com/odoo/enterprise/pull/41336

This change keeps the Point of Sale IoT interface aligned with recent updates in the main Odoo Point of Sale code. It helps ensure related screens and automated checks continue to work correctly after the underlying layout changed.

community: https://github.com/odoo/odoo/pull/122035