fix: 🐛 update the OpenAPI spec
Missing:
- [x] ensure we documented all the status codes: missing: <strike>400 (BAD_REQUEST)</strike> (removed 400 from the code with [d4ee7a5](https://github.com/huggingface/datasets-server/pull/1667/commits/d4ee7a5bd32b9c1666e0f1293c8c0292a265e133)), 501 (NOT_IMPLEMENTED)
- [x] ensure the OpenAPI spec is correct (I have some issues in stoplight, some parts are not rendered). It works well in https://redocly.github.io/redoc/?url=https://github.com/huggingface/datasets-server/raw/0e3a700bb3716aad9d90897e844c9d40455a3b6f/chart/static-files/openapi.json#operation/getOptInOutUrls
- [x] move openapi outside of the chart? its size generates issues in the CI, and anyway it does not pertain the chart. See #849.
- [x] validate the openapi spec in the CI <strike>with spectral</strike> -> #446
- [x] fix the e2e test that use openapi (contract testing)

In other PRs:
- document all the X-Error-Code in OpenAPI -> #1671 
- do contract testing on the OpenAPI examples. Maybe use a new field, like `x-contract-testing-url`, to get the URL to test programmatically. Also: create permanent test datasets (like severo/private) in prod that can be used to contract test in prod? -> #518 
- generate OpenAPI spec from the code -> #1670

- test authenticated against authorized, and maybe add examples in the openapi spec -> in #1656 
fix: 🐛 update the OpenAPI spec: Missing:
- [x] ensure we documented all the status codes: missing: <strike>400 (BAD_REQUEST)</strike> (removed 400 from the code with [d4ee7a5](https://github.com/huggingface/datasets-server/pull/1667/commits/d4ee7a5bd32b9c1666e0f1293c8c0292a265e133)), 501 (NOT_IMPLEMENTED)
- [x] ensure the OpenAPI spec is correct (I have some issues in stoplight, some parts are not rendered). It works well in https://redocly.github.io/redoc/?url=https://github.com/huggingface/datasets-server/raw/0e3a700bb3716aad9d90897e844c9d40455a3b6f/chart/static-files/openapi.json#operation/getOptInOutUrls
- [x] move openapi outside of the chart? its size generates issues in the CI, and anyway it does not pertain the chart. See #849.
- [x] validate the openapi spec in the CI <strike>with spectral</strike> -> #446
- [x] fix the e2e test that use openapi (contract testing)

In other PRs:
- document all the X-Error-Code in OpenAPI -> #1671 
- do contract testing on the OpenAPI examples. Maybe use a new field, like `x-contract-testing-url`, to get the URL to test programmatically. Also: create permanent test datasets (like severo/private) in prod that can be used to contract test in prod? -> #518 
- generate OpenAPI spec from the code -> #1670

- test authenticated against authorized, and maybe add examples in the openapi spec -> in #1656 