A simple new view to easily display all activity on a model grouped
by res_id and activity_type_id. Some action are possible like sending
a mail template for all record having an activity with this activity type
and present in the view (depends on the filter).
The view use the Kanban activity view on cells. It could be a good idea
to rename this widget to something like "DropdownActivityView" (maybe
after the freeze)
Task: #1870662
PR: #26272