…itors push tokens

PURPOSE

Allow consolidation of push tokens on visitors and its children.

SPECS

This commit changes the way push tokens are registered onto website.visitors.
Since the refactoring of events and event.tracks, it is now possible to send
push notifications to users having wishlisted a specific track.

Because we were working on the stable branch, we introduced the concept of
parent visitors and children visitors, allowing the following use case:
- You connect on device (PC) 1 on your Odoo Account 'Michel'
- You enable push notifications and wishlist track 'Amazing OXP showcase'
- You then connect on device 2 on your Odoo Account 'Michel'
- The visitor from device 1 becomes a child of the one from device 2
- You enable push notifications on device 2 as well
  -> Ideally, when the 'Amazing OXP showcase' track is about to start, we would
  like to notify both devices, which was made possible by notifying both your
  parent visitor on device 2 as well as its children (here device 1).

This lead to a few issues:
- Complicated code in the website_event_track_social module to determine the
  wishlisted tracks of a visitor, we had to take both the tracks wishlisted by
  that record and also the ones wishlisted by its parent ;
- Having to account for archived visitors when sending push notifications to
  event attendees, since children records are automatically archived ;
- Misleading record count when sending a push notification to the event
  attendees, since it would count both the parent and the children visitors.

This also makes a lot of sense with other visitors implementations:
- A visitor can have multiple leads, all regrouped on its main visitor record ;
- A visitor can have multiple wishlisted tracks, all regrouped on its main
  visitor record ;
- And now a visitor can have multiple push subscriptions, also regrouped on its
  main visitor record.

LINKS

Task-2429652

* industry_fsm{_report}, industry_fsm_sale{_report}, project_enterprise,
  worksheet

PURPOSE:

generic improvements for field services.

SPECIFICATIONS:

- tasks editable list view: use the date range widget for the 'start date' and
  'end date' fields
- Add a graph and pivot view to the 'my tasks' menus
- Rename 'By user' to 'by worker' and 'by worksheet' to 'by worksheet template'
- If either one of the planned_date_begin or planned_date_end fields are set
  then the other one should be required
- Field partner_phone will be visible whether the partner_id field is set or not
  if is_fsm is true
- Stat buttons 'Worksheet' and 'Products' will be visible whether the partner_id
  field is set or not if is_fsm is true
- For tasks, track the field 'worksheet_template_id, planned_date_being,
  planned_date_end' in chatter
- Remove create an option for the field 'worksheet_template_id'
- For worksheet template's list view, fields company_ids, worksheet_count and
  color will be optional and displayed by default

For tasks search view,

- Add search items: stage, project, worksheet template, parent task, sale order,
  tags, and reorder it.
- Add filters: followed tasks, my projects, starred, tasks late,
  tasks in overtime rated tasks
- Add a 'customer' and 'sales order' group bys
- Rename a group by 'Responsible' into 'Assigned to'
- Add group by task above 'start date'
- Remove the 'company' group by and reorder the groups accordingly

For projects search view,

- Add a quick search on the worksheet template and company
- Hide the 'sales order' quick search in field service
- Add a group bys: worksheet template and company

Task-2585357