Resources API always include link

[etj]

Even with the changes done in #12079, when exclude[]=* is added, a link to the resource is always added,

Sample request

 curl -s 'http://10.10.100.5/api/v2/resources?exclude[]=*&include[]=pk'  | jq . 
{
  "links": {
    "next": null,
    "previous": null
  },
  "total": 5,
  "page": 1,
  "page_size": 10,
  "resources": [
    {
      "pk": "5",
      "link": "http://10.10.100.5/api/v2/resources/5"
    },
    {
      "pk": "4",
      "link": "http://10.10.100.5/api/v2/resources/4"
    },
    {
      "pk": "3",
      "link": "http://10.10.100.5/api/v2/resources/3"
    },
    {
      "pk": "2",
      "link": "http://10.10.100.5/api/v2/resources/2"
    },
    {
      "pk": "1",
      "link": "http://10.10.100.5/api/v2/resources/1"
    }
  ]
}

Note that the initial requirement was #7529, implemented in #7530 , where the new class BaseDynamicModelSerializer adds the link info into the representation, with no way to remove such info.

Moving such field as an ephemeral field in the Serializer would make the various rest logic to handle the content properly, so that it could be removed and added at will using proper query parameters.