 Mail Activity Mixin is a mixin class to use if you want to add activities
    management on a model. It works like the mail.thread mixin. It defines
    an activity_ids one2many field toward activities using res_id and res_model_id.
    Various related / computed fields are also added to have a global status of
    activities on documents.

    Activities come with a new JS widget for the form view. It is integrated in the
    Chatter widget although it is a separate widget. It displays activities linked
    to the current record and allow to schedule, edit and mark done activities.

    There is also a kanban widget defined. It defines a small widget to integrate
    in kanban vignettes. It allow to manage activities directly from the kanban
    view. Use widget="kanban_activity" on activitiy_ids field in kanban view to
    use it.

    Some context keys allow to control the mixin behavior. Use those in some
    specific cases like import

     * ``mail_activity_automation_skip``: skip activities automation; it means
       no automated activities will be generated, updated or unlinked, allowing
       to save computation and avoid generating unwanted activities;
    