When clicking on "Other activities" in the systray, a list of activities
assigned to the user for which he has no access to underlying record is
displayed. The default list allows to delete, archive, duplicate, ...
activities but what we want is a readonly view. We add here a new view that
doesn't allow any modification on the activities by removing those actions.
Unfortunately, archive and unarchive action is not controllable with an
attribute (nor by setting the active field as readonly in the view), so we
create a very simple extension of the list view to disable it.
We also add in the list view a button to mark an activity as done and a simple
form view to see the details of the activity (note, ...). The "mark as done is
not added in the form view as the activity is deleted causing an error because
the form is still displayed and the record is gone.
Note that those action are only removed from the client but the actions are
not forbidden on the server side.
Task-3562098
Part-of: odoo/odoo#139917