Provide URL generation and cross launching via pod annotations

[fredhsu]

I would like to be able to provide a URL to a external tool by annotating a pod, and see the URL show up in the Hubble UI to enable cross launching. In this use case it would be helpful to be able to combine data from multiple annotations to generate the final URI. For instance if the pod is annotated with url=http://www.github.com and endpoint=cilium, you could combine them to the full http://www.github.com/cilium and provide that as a hyperlink in one of the views of the pod.