add k8s manifests and Helm Chart

[cmdoret]

This PR defines a helm chart to deploy the Gimie API to a kubernetes cluster.

Among other things, this allows to:

• Deploy multiple replicas (3 by default) accessible at the same address with automatic load balancing.
• Automatically restart container in case of problems.
• Deploy rolling updates without downtime.

Usage instructions are available in gimie-api/README.md.

Caveats of the current setup:

• The service uses the personal token provided by the person who deploys it.
• It needs a (public) docker image, currently cmdoret/gimie-api-container.

[caviri]

Soo Cool @cmdoret, I'm checking it. Do you think that docker image can be modified by one at ghcr.io?

[cmdoret]

Update: Took in updates from main +

• use ~= (compatible release operator, PEP440) when specifying dependencies in Dockerfile
  • it locks only the major version to allow security patches and bugfixes, but not beaking backward-compatibility (assuming SemVer).
• update github namespace throughout the repo (SDSC-ORD -> sdsc-ordes)
• upload image to github container registry and refer to it in helm chart