feat(nas): Add first S3 passthrough ingress

This patch introduces a simple ingress proxy for the S3 storage located
on my NAS by using a Service of type "externalName", which acts like a
CNAME for an external dns entry and allows to create an ingress object,
which can handle traffic for this service. This way, everything passes
through the central nginx proxy and can be managed through Kubernetes
instead of exposing the NAS directly to the internet.

References:
https://kubernetes.io/docs/concepts/services-networking/service/#externalname
https://kubernetes.io/docs/concepts/services-networking/ingress/