Add access count to /roles/ and /roles/<uuid>/ endpoints

[coderbydesign]

This adds an accessCount field to the /roles/ and /roles/<uuid>/ endpoints, to show the number of permission/access objects contained within each role.

To do so, we're annotating the base query for roles with the access count, and including it as a read-only value in the serializers.

New Response for /roles/

{
  "meta": {
    "count": 2508,
    "limit": 1,
    "offset": 0
  },
  "links": {
    "first": "/api/rbac/v1/roles/?limit=1&offset=0",
    "next": "/api/rbac/v1/roles/?limit=1&offset=1",
    "previous": null,
    "last": "/api/rbac/v1/roles/?limit=1&offset=2507"
  },
  "data": [
    {
      "uuid": "3ecac858-4f48-4393-a26b-914ba73477aa",
      "name": "Ansible Automation Access",
      "description": "An all access role which grants read and write permissions.",
      "created": "2020-01-31T16:44:43.919593Z",
      "modified": "2020-01-31T16:44:43.946095Z",
      "policyCount": 1,
      "accessCount": 2,
      "applications": [
        "inventory",
        "ansible-automation"
      ],
      "system": true,
      "platform_default": true
    }
  ]
}

New Response for /roles/<uuid>/

{
  "uuid": "3ecac858-4f48-4393-a26b-914ba73477aa",
  "name": "Ansible Automation Access",
  "description": "An all access role which grants read and write permissions.",
  "access": [
    {
      "permission": "inventory:*:*",
      "resourceDefinitions": []
    },
    {
      "permission": "ansible-automation:*:*",
      "resourceDefinitions": []
    }
  ],
  "policyCount": 1,
  "accessCount": 2,
  "applications": null,
  "system": true,
  "platform_default": true,
  "created": "2020-01-31T16:44:43.919593Z",
  "modified": "2020-01-31T16:44:43.946095Z"
}

[wcmitchell]

👍