List available envelope owners

{
  "items": [
    {
      "id": "483e52a8-2811-454d-b2cc-3e6d420d8dee",
      "name": "John Doe",
      "isActive": true,
      "isCurrent": false,
      "role": "Administrator",
      "avatar": "https://example.com/avatar.jpg"
    }
  ]
}