Need build for resource-backend

[johnbelamaric]

I built it from https://github.com/nokia/k8s-ipam and pushed it as nephio/resource-backend:latest, which is what the package expects. But we probably need to automate this in some way. Perhaps if the repo makes its way to nephio-project at some point.

cc @henderiw @radoslawc

[adetalhouet]

Can this be at least captured in the release notes, until a decision is made through nephio-project/nephio#45 ?