The spreadsheet selection dialog was redesigned so different spreadsheet areas can share the same experience without custom front-end work each time. This makes it easier and safer to add new spreadsheet-related features in Documents and Dashboards while keeping the user experience consistent.

The spreadsheet editing module’s automated tests were reorganized and converted to a newer testing framework. This is an internal quality improvement that helps maintain reliability while preserving legacy support needed by related modules.

This commit converts the tests of the spreadsheet_edition module to Hoot.
Some legacy helpers are kept because they are used in other modules.

Task: 4011296

A spreadsheet-related helper and its internal tests were removed from Enterprise because the logic now lives in the shared spreadsheet library. This reduces duplicate maintenance and helps keep spreadsheet behavior consistent across products.

This commit delete the helper `mergeContiguousZones` and its tests from enterprise, as they were moved to the o-spreadsheet library.

Task: [3965270](https://www.odoo.com/web#id=3965270&cids=1&menu_id=4720&action=333&active_id=2328&model=project.task&view_type=form)