Contacts in several partners

No new fields.

• read(self, fields=None, context=None, load='_classic_read')

• contact_id Many2one → res.partner
  domain=[('is_company', '=', False), ('contact_type', '=', 'standalone')] string='Main Contact' args: 'res.partner'
• contact_type Selection
  compute='_compute_contact_type' default='standalone' index=True store=True args: [('standalone', 'Standalone Contact'), ('attached', 'Attached to existing Contact')]
• other_contact_ids One2many → res.partner
  string='Others Positions' args: 'res.partner', 'contact_id'

• create(self, vals_list)
  @api.model_create_multi
  When creating, use a modified self to alter the context (see comment in _basecontact_check_context). Also, we need to ensure that the name on an attached contact is the same as the name on the contact it is attached to.
• read(self, fields=None, load='_classic_read')
• search(self, args, offset=0, limit=None, order=None, count=False)
  @api.model
  Display only standalone contact matching ``args`` or having attached contact matching ``args``
• unlink(self)
• update_contact(self, vals)
• write(self, vals)