*: board, website
This commit simplifies the UX of the 'Custom Group by' menu. Before this
commit, many clicks were needed to apply another filter, from an accordion
menu.
Now, a select element is used instead, allowing a better user experience, by
enabling such group by directly, when an option is selected.
Some tests have been adapted to the new selectors and behaviors, and the
applyGroup and toggleAddCustomGroup has been removed, since groups are applied
when selected, and the value can be modified directly with selectGroup.
task-3458519
closesodoo/odoo#132006
Signed-off-by: Mathieu Duckerts-Antoine (dam) <dam@odoo.com>