Feature Request: Enable credentials to be passed to the build for reading priveleged assets

For the build of the api-spec-host, we use the hugo preview and deployment pipeline. While this works for a majority of use cases, there is currently no way to embed additional credentials into the build container. This is needed by the api-spec-host project as it needs to read private Gitlab resources at build time to fetch specifications for projects that can't be public due to security concerns, or in some cases, because of embedded GPL code that we cannot redistribute.