Add optional OIDC avatar fetching from the “picture” claim

[bookstack] / dev / api / responses / users-list.json

{
  "data": [
    {
      "id": 1,
      "name": "Dan Brown",
      "email": "[email protected]",
      "created_at": "2022-02-03T16:27:55.000000Z",
      "updated_at": "2022-02-03T16:27:55.000000Z",
      "external_auth_id": "abc123456",
      "slug": "dan-brown",
      "last_activity_at": "2022-02-03T16:27:55.000000Z",
      "profile_url": "https://docs.example.com/user/dan-brown",
      "edit_url": "https://docs.example.com/settings/users/1",
      "avatar_url": "https://docs.example.com/uploads/images/user/2021-10/thumbs-50-50/profile-2021.jpg"
    },
    {
      "id": 2,
      "name": "Benny",
      "email": "[email protected]",
      "created_at": "2020-01-15T04:43:11.000000Z",
      "updated_at": "2021-11-18T17:10:58.000000Z",
      "external_auth_id": "",
      "slug": "benny",
      "last_activity_at": "2022-01-31T20:39:24.000000Z",
      "profile_url": "https://docs.example.com/user/benny",
      "edit_url": "https://docs.example.com/settings/users/2",
      "avatar_url": "https://docs.example.com/uploads/images/user/2021-11/thumbs-50-50/guest.jpg"
    }
  ],
  "total": 28
}