Implement better API Key security

[whitlockjc]

When it comes to applications, security is up to them. But the k8s-router does allow you to have some level of security in that you need an API Key to access your deployments. Thankfully this is opt-in and not required but for those that do want it, we need a better solution. Right now the keys are static and created at the namespace level. It would be nice to give the deployment owner more control as to which key(s) to use.

While this is not to be confused with authentication as a service, we could eventually turn this into a lightweight, API Management feature supporting more than just simple keys.

[whitlockjc]

The ability to do this in the future might depend on Dibyo's KVM stuff.