feat(PageContent): set unique ids on nested headers

[bookstack] / dev / api / responses / search-all.json

{
  "data": [
    {
      "id": 84,
      "book_id": 1,
      "slug": "a-chapter-for-cats",
      "name": "A chapter for cats",
      "created_at": "2021-11-14T15:57:35.000000Z",
      "updated_at": "2021-11-14T15:57:35.000000Z",
      "type": "chapter",
      "tags": []
    },
    {
      "name": "The hows and whys of cats",
      "id": 396,
      "slug": "the-hows-and-whys-of-cats",
      "book_id": 1,
      "chapter_id": 75,
      "draft": false,
      "template": false,
      "created_at": "2021-05-15T16:28:10.000000Z",
      "updated_at": "2021-11-14T15:56:49.000000Z",
      "type": "page",
      "tags": [
        {
          "name": "Animal",
          "value": "Cat",
          "order": 0
        },
        {
          "name": "Category",
          "value": "Top Content",
          "order": 0
        }
      ]
    },
    {
      "name": "How advanced are cats?",
      "id": 362,
      "slug": "how-advanced-are-cats",
      "book_id": 13,
      "chapter_id": 73,
      "draft": false,
      "template": false,
      "created_at": "2020-11-29T21:55:07.000000Z",
      "updated_at": "2021-11-14T16:02:39.000000Z",
      "type": "page",
      "tags": []
    }
  ],
  "total": 3
}