Save authentication tokens temporarily

Allows game backends to save access and refresh tokens temporarily, returning a short code challenge that can be passed via launcher deeplinks.

curl -X POST "https://test-api.stash.gg/sdk/launcher/tokens/save" \  -H "Content-Type: application/json" \  -d '{    "accessToken": "string",    "refreshToken": "string"  }'

{
  "codeChallenge": "string"
}

{
  "code": 0,
  "message": "string",
  "details": [
    {
      "@type": "string",
      "property1": null,
      "property2": null
    }
  ]
}