Add a nginx reverse proxy in front of the API

[severo]

It will allow to:

1. serve the assets directly
2. cache the responses

The image: should point to the official nginx docker image
The nginx config can be generated as a ConfigMap:

• see https://github.com/huggingface/gitaly-internals/blob/main/kube/gitaly/templates/gitaly/config.yaml
• mounted as a volume
• see https://github.com/huggingface/datasets-server/blob/af9a93d4b810c2353de01369ad49f2065272af85/services/api/INSTALL.md for the content of the config (cache + assets/)

[severo]

Fixed by #245