Modify the data models for items

The current datamodel for items is as follows

{
  'id': string,
  'itemId': string,
  'itemType': string,
  'levelId': string,
  'levelName': string,
  'levelNumber': number,
  'tagId': string,
  'tagName': string,
  'tagType': string,
}

According to @ankushdharkar's comments here, we should change this as follows.

{
  "id":"string",
  "item":{
    "id":"string",
    "type":"string"
  },
  "level":{
    "id":"string",
    "name":"string",
    "number":"number"
  },
  "tag":{
    "id":"string",
    "name":"string",
    "type":"string"
  }
}

No files, tests, or entry points are identified in the issue. Locate the item data model and its consumers, then update the representation to use nested item, level, and tag objects while preserving the stated fields; done means the model and affected uses match the proposed schema.