Window actions for client side paging

This is a technical module for developers. It adds three new action types that a server action or a Python method can return: one to go to the previous record, one to go to the next record, and one to switch to the list view. When such an action is returned, the form view's pager moves in the requested direction on the client side, so the user sees the next or previous record in the same form without a full page reload.

A typical use case is a validation flow: you open a list of records to validate, open the first one in a form, validate it, and the validation method returns the "next" action so the user is automatically taken to the next record.

The module also patches the pager component so it listens for navigation events and performs the move. It includes a demo that adds two buttons, "Previous Partner" and "Next Partner", on the partner form (res.partner) to illustrate and test the behaviour. These buttons are only for demonstration and testing; developers are expected to return the action types from their own code instead.

The module depends only on web and does not add menus or business rules of its own.