Get all available roles including default as well as custom roles

{
  "result": [
    {
      "id": "64ced5a8-c2b9-4421-821a-4e32bdfaaecc",
      "title": "Contributor",
      "title_key": null,
      "description": "An editor or draft writer with no admin access.",
      "description_key": null,
      "is_system_role": true,
      "is_portal_role": true
    },
    {
      "id": "c1b8ae08-78d5-41d9-b3c4-3b0892b05ca8",
      "title": "Owner",
      "title_key": null,
      "description": "",
      "description_key": null,
      "is_system_role": true,
      "is_portal_role": true
    },
    {
      "id": "264485a9-088e-49bf-b33e-a417e9fa01e5",
      "title": "Admin",
      "title_key": null,
      "description": "Admin has access to everything except billing.",
      "description_key": null,
      "is_system_role": true,
      "is_portal_role": true
    },
    {
      "id": "88ec9ab0-2355-46b6-8eed-b3ce2cd870a8",
      "title": "None",
      "title_key": null,
      "description": "No content scope assigned. This role can be changed later.",
      "description_key": null,
      "is_system_role": true,
      "is_portal_role": true
    },
    {
      "id": "62810dc1-2d21-422e-bdfb-c3daebf91dd3",
      "title": "Edito",
      "title_key": null,
      "description": "The editor can manage the articles, categories, drive, workflows, and content reuse.",
      "description_key": null,
      "is_system_role": true,
      "is_portal_role": true
    },
    {
      "id": "926c7a3c-0fe8-40c8-a96f-f02c95a12d5c",
      "title": "Draft writer",
      "title_key": null,
      "description": "A draft writer can add or edit the articles/category pages but has limitations publishing them.",
      "description_key": null,
      "is_system_role": true,
      "is_portal_role": true
    }
  ],
  "extension_data": null,
  "success": true,
  "errors": [],
  "warnings": [],
  "information": []
}