Verifies the auth credentials stored in the configuration.

For non-OAuth auth types (API key, bearer token, basic auth), tests whether the stored credentials can successfully connect to the integration. For OAuth2, returns an `authorizationUrl` the frontend should redirect the user to in order to complete the OAuth flow. When the config uses an AuthMap (per-request auth), each entry is verified independently and the results are returned in `authMapResults`. Use the optional `authMapIndex` query parameter to verify a single entry. Returns 400 if the config has neither Auth nor AuthMap configured.

curl -X POST "https://api.fruxon.com/v1/tenants/string/integrations/string/configs/497f6eca-6276-4993-bfeb-53cbbbba6f08:verifyAuth"

{
  "success": false,
  "error": "string",
  "credentialsRejected": false,
  "authorizationUrl": "string",
  "authMapResults": [
    {
      "parameters": {},
      "success": false,
      "error": "string",
      "authorizationUrl": "string"
    }
  ]
}

{
  "type": "string",
  "title": "string",
  "status": 0,
  "detail": "string",
  "instance": "string",
  "property1": null,
  "property2": null
}

{
  "type": "string",
  "title": "string",
  "status": 0,
  "detail": "string",
  "instance": "string",
  "property1": null,
  "property2": null
}