List all registered onboarding providers with their requirements and config

{
  "success": true,
  "data": {
    "providers": [
      {
        "provider": "quidkey",
        "dependencies": [
          "quidkey"
        ],
        "requirements": [
          {
            "code": "LEGAL_ENTITY_EXISTS",
            "label": "Legal entity attached"
          }
        ]
      }
    ]
  }
}